Atomic Mass 4.6 – Electron Energy Levels Chapter 4 4.7 – Electron Configurations 4.8

Lecture Presentation

4.1 – Elements and Symbols 4.2 – The Periodic Table 4.3 – The Atom 4.4 – Atomic Number and Mass Number 4.5 – Isotopes and Atomic Mass 4.6 – Electron Energy Levels Chapter 4 4.7 – Electron Configurations 4.8 – Trends in Periodic Properties

Elements: are pure substances from which all other things are built. are listed on the periodic table.

Goal : Given its name, write its correct symbol; from the symbol. Write the correct name.

General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. Karen C. Timberlake Element names come from planets, mythological figures, Chemical symbols minerals, colors, geographic locations, and famous people. Carbon, C • represent the names of the elements. • consist of one to two letters and start with a capital letter.

One-Letter Symbols Two-Letter Symbols C carbon Co cobalt N nitrogen Ca calcium F fluorine Al aluminum O oxygen Mg magnesium

Write the correct chemical symbols for each of the following elements:

A. iodine B. iron C. magnesium D. zinc E. nitrogen

General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. Karen C. Timberlake Give the names of the elements with the following symbols: Mercury (Hg) Is a silvery, shiny element that is liquid at room A. P temperature. B. Al C. Mn Can enter the body by: mercury vapor inhalation D. H contact with the skin E. K ingestion of water or food contaminated with mercury

Once mercury has entered the body, it destroys proteins, disrupts cell function. Long-term exposure can Damage the brain and kidneys Cause mental retardation Decrease physical development

Mercury contamination comes from • industrial wastes. 4.1 – Elements and Symbols • fish and seafood. 4.2 – The Periodic Table • batteries. 4.3 – The Atom • compact fluorescent bulbs. 4.4 – Atomic Number and Mass Number 4.5 – Isotopes and Atomic Mass 4.6 – Electron Energy Levels 4.7 – Electron Configurations 4.8 – Trends in Periodic Properties Fish absorb mercury. Big fish eat lots of small fish, end up with more mercury. General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. Karen C. Timberlake Karen C. Timberlake The Periodic Table

The periodic table organizes 118 elements into groups with similar properties and places them in order of increasing atomic mass.

Goal : Use the periodic table to identify the group and the period of an element; identify the element as a metal, a nonmetal, or a metalloid.

Group numbers are written at the top of each vertical column (1-18). In the periodic table,

elements are arranged according to properties.

Vertical columns Periods are represent groups of numbered elements 1-7 and horizontal rows represent periods.

The heavy zigzag line separates metals and nonmetals. Silver Metals (Metal) Nonmetals • Metals are located to the left. Solid at room temp Dull (not shiny / ) • Nonmetals are located to the right. Exception: mercury brittle • Metalloids are located along the heavy zigzag line. Shiny! Not ductile Ductile (shaped into wires) Not malleable Malleable (hammered Poor conductors flat into sheets) Low melting points Good conductors Low densities (many are High melting points gasses at room temp.)

Antimony Sulfur (metalloid) (nonmetal)

General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. Karen C. Timberlake Metalloids have a combination of metal and nonmetal properties. Characteristics of Metalloids

Silver (Metal) Metalloids, located along the heavy zigzag line on the periodic table exhibit properties of metals and nonmetals. • are better conductors than nonmetals but not as good as metals. • are used as semiconductors and insulators, because they can be modified to function as conductors or insulators.

Antimony Sulfur (metalloid) (nonmetal)

General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. Karen C. Timberlake Study Check Study Check List all of the elements that match the B. nonmetals in Group 15 description. Bi, N, P, As, Sb Identify each of the following elements as a A. metals in Group 14 C. metalloids in Group 14 metal, a nonmetal, or a metalloid: Sn, Pb, C, Si, Ge C, Si, Ge, Sn, Pb A. sodium B. chlorine C. silicon D. iron E. carbon

Group 1, the alkali metals, includes the following: Soft • lithium (Li) Shiny Good • sodium (Na) conductors • potassium (K) Low melting • rubidium (Rb) points React • cesium (Cs) vigorously with • Francium (Fr) water!

Group 2 elements, the alkaline Group 17, the halogens, earth metals, are shiny but not as includes the following: reactive as Group 1A metals. They • fluorine (F) include the following: • chlorine (Cl) • beryllium (Be) • bromine (Br) • magnesium (Mg) • iodine (I) • calcium (Ca) • astatine (At) • strontium (Sr) • barium (Ba) • radium (Ra)

Strontium gives the red color in fireworks. General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. Karen C. Timberlake Karen C. Timberlake Noble Gases Study Check

Group 18, the noble Identify the element described by each of the following gases, include: groups and periods:

Helium (He) 1. Group 17, Period 4 Neon (Ne) 2. Group 2, Period 3 Argon (Ar) Krypton (Kr) 3. Group 15, Period 2 Xenon (Xe) Radon (Rn)

Of all the elements, 23 are essential for the well-being and survival of the human body. 4.1 – Elements and Symbols 4.2 –The Periodic Table 4.3 – The Atom 4.4 – Atomic Number and Mass Number 4.5 – Isotopes and Atomic Mass 4.6 – Electron Energy Levels 4.7 – Electron Configurations 4.8 – Trends in Periodic Properties

The Atom

An atom is the smallest particle of an element that retains the characteristics of that element.

Aluminum foil contains atoms of aluminum.

Goal : Describe the electrical charge and location in an atom for a proton, a neutron, and an electron

Atoms contain the following Atoms contain the following subatomic particles: subatomic particles: • protons have a positive (+) charge • Protons • neutrons have no charge (neutral) • Neutrons • electrons have a negative (-) charge • Electrons

Structure of the Atom Structure of the Atom

An atom consists of a nucleus, located in the center of the atom, that contains protons and neutrons and represents most of the mass of an atom. electrons that occupy a large, empty space around the nucleus.

In an atom, the protons and neutrons that make up almost all the mass are Protons – positive charge packed into the tiny volume of the nucleus. The rapidly moving electrons Neutrons – neutral (negative charge) surround the nucleus and account for the large volume Electrons – negative charge of the atom.

In Dalton䇻s atomic theory, atoms Because the mass of subatomic particles are so small, • are tiny particles of matter. • chemists use a very small unit of mass called the atomic • of an element are similar to each other and different mass unit (amu). from those of other elements. • of two or more different elements combine to form • 1 amu has a mass equal to 1/12 of the mass of the compounds. carbon-12 atom that contains six protons and six neutrons. • are rearranged to form new combinations in a • 1 amu = 1 Dalton (Da) in biology. chemical reaction. • 1 amu = 1.66 x 10-27kg • Electrons have such a small mass that they are not included Atoms are never created or destroyed during a chemical in the mass of an atom. reaction.

Subatomic Particles in the Atom

If a proton has a mass of 1.67 x 10-27 kg, what is its mass in amu? Protons and neutrons have a very small mass. Electrons are 1800 times smaller than protons and neutrons.

Which of the following subatomic particles fits each of the descriptions below? 4.1 – Elements and Symbols protons, neutrons, or electrons 4.2 –The Periodic Table 4.3 – The Atom A. found outside the nucleus 4.4 – Atomic Number and Mass Number B. have a positive charge 4.5 – Isotopes and Atomic Mass C. have mass but no charge 4.6 – Electron Energy Levels 4.7 – Electron Configurations 4.8 – Trends in Periodic Properties

Each element is assigned an atomic number.

The atomic number is equal to the number of protons in an atom (and is always a whole number). • The same for all atoms of an element • Appears above the symbol of an element in the periodic table.

Goal : Given the atomic number and the mass number of an atom, state the number of protons, neutrons, and electrons.

Atomic number = number of protons

the atomic number of H is 1; every H atom has one proton.

the atomic number of C is 6; every C atom has six protons.

the atomic number of Cu is 29; every Cu atom has 29 protons.

All atoms of lithium (left) contain three protons, and all atoms of carbon (right) contain six protons.

For neutral atoms, the net charge is zero. Use the periodic table to fill in the atomic number, number of protons, and number of electrons for each of the following number of protons = number of electrons elements: Element Atomic Protons Electrons Number Aluminum has 13 protons and 13 electrons. The net (overall) charge is zero. N Zn 13 protons (13+) + 13 electrons (13–) = 0 S

The mass number Number of protons = atomic number • represents the number of particles in the nucleus. Number of protons + neutrons = mass number • is equal to the number of protons + the number of neutrons. • is always a whole number. Number of neutrons = mass number – atomic number • does not appear in the periodic table.

Charge of atom = Number of electrons + Number of protons

Number of electrons = charge – number of protons

An atom of lead (Pb) has a mass number of 207. An atom of titanium (Ti) has a mass number of 44.

A. How many protons are in the nucleus? A. How many protons are in the nucleus?

B. How many neutrons are in the nucleus? B. How many neutrons are in the nucleus?

C. How many electrons are in the atom? C. How many electrons are in the atom?

General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. Karen C. Timberlake Karen C. Timberlake 4.1 – Elements and Symbols 4.2 –The Periodic Table 4.3 – The Atom 4.4 – Atomic Number and Mass Number 4.5 – Isotopes and Atomic Mass 4.6 – Electron Energy Levels 4.7 – Electron Configurations 4.8 – Trends in Periodic Properties Goal : Determine the number or protons, electrons, and neutrons in one or more of the isotopes of an element; calculate the atomic mass of an element using the percent abundance and mass of its naturally occurring isotopes.

Isotopes Atomic Symbols: Subatomic Particles

Isotopes Given the atomic symbols, determine the number of • are atoms of the same element. protons, neutrons, and electrons. • have the same number of protons but different numbers 16 31 65 of neutrons. 8 O 15 P 30 Zn • (different mass numbers) • can be distinguished by their atomic symbols.

Naturally occurring carbon consists of three isotopes: 12C, Write the atomic symbols for atoms with the following 13C, and 14C. State the number of protons, neutrons, and subatomic particles: electrons in each of the three isotopes.

A. 8 protons 8 neutrons 8 electrons

B. 17 protons 20 neutrons 17 electrons

C. 47 protons 60 neutrons 47 electrons

1. Which of the pairs below are isotopes of the same element? Most elements have several isotopes that occur in nature (vs. made in a lab.) 2. Which of the pairs below have the same number of neutrons? These isotopes are called “naturally occurring.”

AB C Chlorine has 3 isotopes: 35Cl 36Cl 37Cl

15 15 12 14 15 16 Only 35Cl and 37Cl happen naturally. X X X 6 X X X 8 7 6 7 8 36Cl has to be made in a lab.

So chlorine has 2 naturally occurring isotopes.

Atomic mass is the weighted average of all naturally occurring isotopes of that element. number on the periodic table below the chemical symbol.

Chlorine, with two naturally occurring isotopes, has an atomic mass of 35.45 amu.

Magnesium, with three naturally occurring isotopes, has an atomic mass of 24.31 amu.

Magnesium’s atomic mass: 24.31 amu.

To calculate atomic mass, use the experimental percent abundance of each isotope of the element. multiply the percent abundance (divided by 100) by the atomic mass of that isotope. sum the total mass of all isotopes.

Gallium is an element found in lasers used in CD players. In a sample of gallium, there is 60.10% of 69Ga atoms (atomic mass 68.926) 39.90% of 71Ga atoms (atomic mass 70.925) What is the atomic mass of gallium?

4.8 – Trends in Periodic Properties Goal: Describe the energy levels, sublevels, and orbitals for the electrons in an atom.

We experience electromagnetic radiation in different Light and other electromagnetic radiation consists of forms, such as light, the colors of a rainbow, or X-rays. energy particles that move as waves of energy. • The distance between the peaks of waves is called the wavelength. • High-energy radiation has shorter wavelengths. • Low-energy radiation has longer wavelengths.

All electromagnetic radiation travels Light is pure energy! at the speed of light! (3 x 108 m/s!)

Electromagnetic Spectrum

A rainbow appears when sunlight reflects through a raindrop and is separated into its different EM radiation.

The same thing happens when you shine sunlight through a glass prism! The Electromagnetic Spectrum above shows all types electromagnetic waves. Many of which we use every day!

The lines of color in an atomic spectrum are caused by the behavior of that element’s Scientists found that when they used electrons. a different light source than the sun, they didn’t always get a full rainbow! Electrons occupy specific areas around the atom they are a part of.

They found that each element had it’s own “fingerprint” based on which light it produced. We now call it an element’s atomic spectrum Each electron has a specific energy level which corresponds to the “ring” the electron resides in.

In an atom, each electron has a specific energy, • Electrons with the same known as its energy level, which energy are grouped in the same energy level. is assigned principal quantum numbers (n) = (n = 1, n = 2, …). • Energy levels are assigned values called principal increases in energy as the value of n increases and electrons are farther away from the nucleus. quantum numbers (n), (n = 1, n = 2, …). The energy of an electron is quantized—electrons can have only specific energy values.

An electron can have only the energy of one of the energy levels in an atom.

It is the arrangement of electrons Electrons move to a that determines the physical and higher energy level chemical properties of an element. when they absorb energy. • Each energy level consists of one or more sublevels. When electrons fall back to a lower energy level, light is emitted. The energy emitted or absorbed is equal to the differences between the two •The number of sublevels in an energy level is energy levels. equal to the principal quantum number n of that energy level. •The sublevels are identified as s, p, d, and f. •The order of sublevels in an energy level is s < p < d < f

The location of an electron is described in terms of probability. • Orbitals are a three- dimensional volume in which electrons have the highest probability of being found. • The s orbitals are spheres.

(a) The electron cloud of an s orbital represents the highest probability of finding an s electron. (b) The s orbitals are shown as spheres. The sizes of the s orbitals increase because they contain electrons at higher energy Up to 2 electrons can fit in each “box” (orbital) levels.

There are three p orbitals, starting with n = 2. • Each p orbital has two lobes, like a balloon tied in the middle, and can hold a maximum of two electrons. • The three p orbitals are arranged perpendicular to each other along the x, y, A p orbital has two regions of high probability, which gives a “dumbbell” shape. (a) and z axes around the Each p orbital is aligned along a different axis from the other p orbitals. (b) All nucleus. three p orbitals are shown around the nucleus.

Each of the d sublevels contains five d orbitals. There are five d orbitals, starting with n = 3. • Four of the five d orbital has four lobes, in the Four of the five d shape of a 4-leaf clover. orbitals consist of four lobes that are • The only difference aligned along or between them is their between different location. Shape is axes. One d orbital identical. consists of two lobes and a doughnut- • The 5th d orbital looks shaped ring around like a p orbital with a its center. donut around its middle.

Each orbital can hold to two electrons.

Up to 2 electrons can fit in each “box” (orbital)

Orbital Capacity and Electron Spin

electrons in the same orbital repel each other. The Pauli exclusion principle states that electrons in the same orbital must have each orbital can hold a maximum of two their magnetic spins cancel (they must electrons. spin in opposite directions). We can represent magnetic spins with electrons in the same orbital repel each other. arrows electrons in the same orbital must have their magnetic spins cancel (they must spin in opposite directions).

Summary: Each orbital can have up to 2 electrons with one “spin up” and the other “spin down”

There is a maximum number of electrons that can fill each sublevel. Each s sublevel has one orbital and can hold a maximum of two electrons. Each p sublevel has three orbitals and can hold a maximum of six electrons. Each d sublevel has five orbitals and can hold a maximum of 10 electrons. Each f sublevel can has 7 orbitals and can hold a maximum of 14 electrons.

4.1 – Elements and Symbols 4.2 –The Periodic Table 4.3 – The Atom 4.4 – Atomic Number and Mass Number 4.5 – Isotopes and Atomic Mass 4.6 – Electron Energy Levels 4.7 – Electron Configurations 4.8 – Trends in Periodic Properties Goal: Draw the orbital diagram and write the electron configuration for an element.

An orbital diagram shows the placement of electrons in the We fill an orbital diagram with the number of electrons an atom has. orbitals in order of increasing energy. Element Atomic # # of electrons

This is much easier than Hydrogen (H) trying to draw all the orbital shapes. Helium (He) There is 1 s orbital, so there is 1 box. Begin at the bottom of the chart, putting two electrons in each orbital (box). There are 3 p orbitals, so Use an arrow to there are 3 boxes represent an representing it. electron. Etc. If there are two electrons in one orbital, make one “up” and one Hydrogen Helium “down” General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. Karen C. Timberlake Karen C. Timberlake

Orbital diagrams can also be written on one line to save space. Finally, orbital diagrams can also be written using the orbital They are written in the order of lowest energy to highest. names and number of electrons as:

Hydrogen Helium

We call this format the electron configuration of that atom or element.

Chemists use a notation called electron configuration to Element Atomic # # of electrons

• indicate the placement of electrons in an atom. Lithium • show how electrons fill energy levels and sublevels in order of increasing energy. • write an abbreviated form using a noble gas to represent all electrons preceding it.

Electron Configuration for Carbon

Element Atomic # # of electrons Element Atomic # # of electrons

Beryllium Boron

Carbon

Nitrogen

Place one electron in each p orbital before doubling up. (same for d and f orbitals)

Element Atomic # # of electrons

Oxygen

Fluorine

Neon

Place one electron in each p orbital before doubling up. (same for d and f orbitals)

General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. General, Organic, and Biological Chemistry: Structures of Life, 5/e © 2016 Pearson Education, Inc. Karen C. Timberlake Karen C. Timberlake Period 3: Sodium to Argon Electron Configurations and the Periodic Table The electron configurations of elements are related to their positions on the periodic table. Different sections or blocks correspond to sublevels s, p, d, and f.

1. The s block contains elements in 1 and 2. This means the 3. The d block, which contains transition elements, first appears after final one or two electrons are in the s sublevel. calcium (atomic number 20). There are 10 elements in the d block, because five d orbitals can hold a maximum 2. The p block consists of elements in Group 13 to Group 18. of 10 electrons. There are six p block elements in each period, because 4. The f block, the inner transition elements, is the two rows of three p orbitals can hold a maximum of six electrons. elements at the bottom of the periodic table. There are 14 elements in each f block, because seven f orbitals can hold a maximum of 14 electrons.

Writing Configurations Using Sublevel Blocks Electron Configurations: d and f block

STEP 1 Locate the element on the periodic table. Beginning in Period 4, STEP 2 Write the filled sublevels in order, going across the 4s sublevel fills before the 3d sublevel, because the 3d each period. sublevel is slightly lower in energy than the 4s sublevel. the 5s sublevel fills before the 4d sublevel. Example: Chlorine the 6s sublevel fills before the 5d sublevel.

Use the sublevel blocks on the periodic table to write the For chromium (Cr), moving one of the 4s electrons to the 3d sublevel adds 1 5 electron configuration for selenium. stability with a half-filled d subshell, and the resulting configuration is 4s 3d .

For copper (Cu), moving one of the 4s electrons to the 3d sublevel adds stability with a filled d subshell, and the resulting configuration is 4s13d10.

Use the sublevel blocks on the periodic table to write the Use the periodic table to give the symbol and name for the electron configuration for rhenium (Re). element with the electron configuration of 1s22s22p63s23p64s23d7.

Write the electron arrangement for the following elements:

4.1 – Elements and Symbols C 1s 4.2 –The Periodic Table 2s 2p 4.3 – The Atom Si 3s 3p 3d 4.4 – Atomic Number and Mass Number 4s 4p 4d 4f 4.5 – Isotopes and Atomic Mass 4.6 – Electron Energy Levels O 5s 5p 5d 5f 4.7 – Electron Configurations 6s 6p 6d 6f 4.8 – Trends in Periodic Properties 7s 7p 7d 7f

Valence Electrons

• Most properties of elements are due to the behavior of the electrons in the element’s outermost orbitals. • Valence electrons are the number of electrons in the outermost energy level.

Goal: Use the electron configurations of elements to explain the trends in periodic properties.

Using the periodic table, how many valence electrons do each element have?

A. calcium

B. lead

Lewis symbols represent the valence electrons as dots Write the electron-dot (Lewis) symbol for each of the placed on sides of the symbol for an element. following elements: • One to four valence electrons are arranged as single dots. • Five to eight valence electrons are arranged with at least one pair of electrons around the symbol for the element. Cl C N HHeBSKr

Remember, with valence electrons, it doesn’t matter which row (period) you are in. Only the column (group).

Atomic size The atomic size increases going down a group and right to left across a period. • is determined by the atom’s atomic radius, the distance between the nucleus and the outermost electrons.

Given the elements C, N, and Cl,

Atomic size increases top to bottom down a group Because each period adds more orbitals which are increasingly A. which is the largest atom? farther from the nucleus. Atomic size increases from left to right Because as you right along a period, you are adding more protons and electrons (but have the same orbitals.) This creates a stronger attraction between the nucleus (protons) and the electrons and it sucks the electrons in tighter. Making the atom smaller.

Ionization energy is the energy required to remove one of Ionization energy increases up the outermost (valence) electrons. a group and increases going across a period from left to right.

• As the distance from the nucleus to the valence electrons increases, the ionization energy decreases. • The ionization energy is low for metals and high for the nonmetals.

Given the elements C, N, and Cl, An element with metallic character is one that loses valence electrons easily (low ionization energy).

B. which has the highest ionization energy? Metallic character • is more prevalent in metals on the left side of the periodic table. • is less for nonmetals on the right side of the periodic table that do not lose electrons easily. • decreases going down a group, as electrons are farther away from the nucleus.

The metallic character of the s and p block elements increases going down a group and increases going from right to left across a period.