The Periodic Table of the Elements

All matter is composed of elements.

All of the elements are composed of atoms. An atom is the smallest part of an element which still retains the properties of that element. All of the elements are listed on the Periodic Table by their Chemical Symbol

• The chemical symbol for every element is either one capital letter or one capital letter plus a small letter

For example: C = carbon Ca = calcium Cl = chlorine Cr = chromium Chemical Symbols

Chemical Symbols • represent name of element • consist of one to two letters and start with capital 1-Letter Symbols 2-Letter Symbols C carbon Co cobalt N nitrogen Ca calcium F fluorine Al aluminum O oxygen Mg magnesium

3 Refer to Table 4.2 on Page 97 for list of the more common elements and their symbols. All of the elements on the Periodic Table are arranged in vertical columns called “Groups”, and in horizontal rows called “Periods”.

All of the groups have numbers and they are either “A” groups or “B” groups running from left to right on the Periodic Table Periodic Table of the Elements

Group**

Period 1 18 IA VIIIA 1A 8A

1 2 13 14 15 16 17 2 1 H IIA IIIA IVA VA VIA VIIA He 1.008 2A 3A 4A 5A 6A 7A 4.003

3 4 5 6 7 8 9 10 2 Li Be B C N O F Ne 6.941 9.012 10.81 12.01 14.01 16.00 19.00 20.18

11 12 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 3 Na Mg IIIB IVB VB VIB VIIB ------VIII --- IB IIB Al Si P S Cl Ar 22.99 24.31 3B 4B 5B 6B 7B ---- 1B 2B 26.98 28.09 30.97 32.07 35.45 39.95 ------8 ------19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 4 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 39.10 40.08 44.96 47.88 50.94 52.00 54.94 55.85 58.47 58.69 63.55 65.39 69.72 72.59 74.92 78.96 79.90 83.80

37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 5 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 85.47 87.62 88.91 91.22 92.91 95.94 (98) 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3

55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 6 Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 132.9 137.3 138.9 178.5 180.9 183.9 186.2 190.2 190.2 195.1 197.0 200.5 204.4 207.2 209.0 (210) (210) (222)

87 88 89 104 105 106 107 108 109 110 111 112 114 116 118 7 Fr Ra Ac~ Rf Db Sg Bh Hs Mt ------(223) (226) (227) (257) (260) (263) (262) (265) (266) () () () () () ()

58 59 60 61 62 63 64 65 66 67 68 69 70 71 Lanthanide Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Series* 140.1 140.9 144.2 (147) 150.4 152.0 157.3 158.9 162.5 164.9 167.3 168.9 173.0 175.0 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Actinide Series~ Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr 232.0 (231) (238) (237) (242) (243) (247) (247) (249) (254) (253) (256) (254) (257)

Learning Check

Give the names of the elements with the following symbols: A. P B. Al C. Mn D. H E. K

7 Solution

Give the names of the elements with the following symbols: A. P = phosphorus B. Al = aluminum C. Mn = manganese D. H = hydrogen E. K = potassium

8 Groups Columns of elements define element groups. Elements within a group share several common properties.

Periods Rows of elements are called periods. The period numbers increase as you go from top to bottom on the periodic table. The number of elements in a period increases as you move down the periodic table. Using grid coordinates (like a checkerboard) each element can be located on the Periodic Table.

Refer to Figure #4.2 on Page 100 Solution

Identify the element described by the following:

1. Group 7A, Period 4 bromine

2. Group 2A, Period 3 magnesium

3. Group 5A, Period 2 nitrogen

11 Learn the names of the groups:

Ia = alkali metals IIa = alkaline earth metals All “B” groups = Transition metals VIIA = halogens VIIIA = noble (inert) gases Classification of Groups Page 101

13 Refer to Page 102

Identify each of the following elements as metal, nonmetal, or metalloid. A. sodium metal B. chlorine nonmetal C. silicon metalloid D. iron metal E. carbon nonmetal

14 STRUCTURE OF THE ATOM: Particles that are smaller than the atom are called subatomic particles. • The three main subatomic particles that form an atom are protons, neutrons, and electrons. The center of the atom is called the nucleus.

Protons and neutrons make up the nucleus of an atom. The atomicAtomic number Number • is specific for each element. • is the same for all atoms of an element. • is equal to the number of protons in an atom. • appears above the symbol of an element.

Atomic Number 11 Symbol Na

16 14 ------Atomic number Si 28.09 ------Mass number An atom is the smallest part of an element which still retains the properties of that element.

An isotope is another form of an element having a different number of neutrons. An element's or isotope's atomic number tells how many protons are in its atoms.

An element's or isotope's mass number tells how many protons and neutrons in its atoms. Subatomic Electrical Particle Mass Charge P 1 +1 N 1 0 e 0 -1 Subatomic Particles in the Atom See Page 108

4.5

21 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. • Protons have a positive electrical charge, so they are often represented with the mark of a "+" sign.

• Neutrons have no electrical charge Learning Check

Identify each statement as describing a 1) proton, 2) neutron, or 3) electron.

A. found outside the nucleus B. has a positive charge C. is neutral D. found in the nucleus

23 Atomic Number

The atomic number • is specific for each element • is the same for all atoms of an element • is equal to the number of protons in an atom • appears above the symbol of an element in the Periodic Table

Atomic Number 11 Symbol Na

24 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Every element, standing alone, in its neutral or uncombined state, MUST have an overall electrical charge of ZERO.

• That means that the number of electrons (negatives) must equal the number of protons (positives). Atoms Are Neutral

For neutral atoms, the net charge is zero. number of protons = number of electrons

Aluminum has 13 protons and 13 electrons. The net (overall) charge is zero. 13 protons (13+) + 13 electrons (13–) = 0

Table 4.6

Use the periodic table to fill in the atomic number, number of protons, and number of electrons for each of the following elements:

Element Atomic Protons Electrons Number N

Use the periodic table to fill in the atomic number, number of protons, and number of electrons for each of the following elements:

Element Atomic Protons Electrons Number N 7 7 7

Zn 30 30 30

S 16 16 16

29 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. • Elements: Each element has a fixed number of positively charged protons in its nucleus and an equal number of electrons orbiting the nucleus. For example, hydrogen (H) has one proton and one electron, but lead (Pb) has 82 protons and 82 electrons. There are about 115 known elements of which 82 are naturally abundant. Study Tips: Protons and Neutrons

Number of protons = atomic number

Number of protons + neutrons = mass number

Number of neutrons = mass number – atomic number

Note: Mass number is given for specific isotopes only.

An atom of lead (Pb) has a mass number of 207. A. How many protons are in the nucleus? B. How many neutrons are in the nucleus? C. How many electrons are in the atom?

An atom of lead (Pb) has a mass number of 207. A. How many protons are in the nucleus? atomic number = 82; number protons = 82

B. How many neutrons are in the nucleus? mass number – number protons = number neutrons 207 – 82 = 125 neutrons

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

C. How many electrons are in the atom? An atom is neutral, which means that the number of electrons is equal to the number of protons. An atom of Pb has 82 protons and 82 electrons.

34 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. This would be the Periodic Table Representation for the normal (stable) isotope of carbon: 6 C 12

This indicates that the normal isotope of carbon has 6 protons and 6 neutrons Atoms of the same element can have different numbers of neutrons; the different possible versions of each element are called isotopes. Isotopes

Isotopes • are atoms of the same element • have different mass numbers • have same number of protons but different numbers of neutrons

Examples of number of subatomic particles for atoms: Atomic symbol

16 31 65 O P Zn 8 15 30

8 p+ 15 p+ 30 p+ 8 n 16 n 35 n 8 e- 15 e- 30 e-

Mass Numbers

24 25 26 12Mg 12Mg 12Mg

Table 4.7

See Page 112

Naturally occurring carbon consists of three isotopes: 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of the following:

Isotope 12C 13C 14C protons neutrons electrons

Naturally occurring carbon consists of three isotopes: 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of the following:

Isotope 12C 13C 14C protons 6 6 6 neutrons 6 7 8 electrons 6 6 6

35 X A.) mercury B.) chlorine C.) scandium D.) bromine E.) selenium

Correct answer Nuclear Notation Standard nuclear notation shows the chemical symbol, the mass number and the atomic number of the isotope. 12 Normal 6C Isotope 14 6C

This notation represents the isotope of carbon which has 8 neutrons, rather than 6 neutrons in the normal (stable)isotope See Page 102 See Page 114 All atoms of any given element have the same mass. The mass of an element is the number beneath its chemical symbol on the periodic table. It represents the average mass of the isotopes that compose that element, weighted according to the natural abundance of each isotope of that element. See Page 113

The atomic mass of chlorine is: •1.) due to all the Cl isotopes. •2.) not a whole number. •3.) the average of two isotopes: 35Cl and 37Cl. Electrons spin and rotate around the outside of the nucleus.

Only a certain number of electrons can be in an energy level at the same time.

The octet rule says that atoms can only have a limited number of electrons in each electron shell. Octet Rule:

The first (innermost) shell is filled with 2 electrons. All of the rest of the shells are filled with 8 electrons The octet rule:

Shell Number Number of electrons 1 2 2 8 3 8 4 8 (18) 5 8 (32) Helium atom model This helium (He) model displays two valence electrons located in its outermost energy level. Helium is a member of the noble gases and contains two protons, neutrons, and electrons.

The valence electrons are the electrons in the last shell or energy level of an atom.

For the “A” Groups on the Periodic Table, the Group Number indicates the number of valence electrons for every element in that group.

Elements in group IA have 1 valence electron. Elements in group IIA have 2 valence electrons. • The number of valence electrons of an element is determined by its periodic table group (vertical column) in which the element is categorized. FOR THE “A” GROUPS ONLY, the number of the group identifies how many valence electrons are contained within the elements listed under that particular column. In the electron level arrangement for the first 18 elements • electrons are placed in energy levels (1, 2, 3, etc.), beginning with the lowest energy level • there is a maximum number in each energy level according to the octet rule. Energy level Number of electrons 1 2 (up to He) 2 8 (up to Ne) 3 8 (up to Ar) 4 2 (up to Ca)

58 Example: 1 The electronic configurations of some of the elements are detailed below. How many valence electrons do the following have?

(a) Al : 2, 8, 3 (Group 3A) (b) Mg: 2, 8, 2 (Group 2A) (c) Cl : 2, 8, 7 (Group 7A) (d) Ca : 2, 8, 8, 2 (Group 2A) Learning Check

Write the electron level arrangement for each:

N = 2, 5 Cl = 2, 8, 7

K = 2, 8, 8, 1

60 All atoms will tend to gain or lose electrons in order to complete their outer shell. Metals will generally lose their outer (valence) electrons to complete their outer shell. Nonmetals will tend to gain electrons to complete their outer shell.

Metalloids may do either. Recommended problems for chapter 4:

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