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UNIT 3 STRUCTURE S AND What is density and how to use it?

A Brief

Structure of an

How to make Ions?

What are Isotopes? DENSITY

Density: is the of a substance per unit , or how much it weighs per given volume UNITS are g/cm3, g/mL, or g/L

Intensive property

Density = mass ÷ volume

You must identify if you are using this equation opposed to dimensional analysis (write the equation out)

Use the correct units for the equation PROPER UNITS FOR DENSITY

All must be in grams (g)

If not in base unit convert all masses into the base unit of grams through dimensional analysis

Volume must be in milliliters (mL) for liquids, cubic centimeters (cm3) for solids, and Liters (L) for gases

Use dimensional analysis to convert to desired units

*** A milliliter (mL) and cubic centimeter (cm3) are the same amount*** DENSITY TRIANGLE

There are three possible variable that you may have to solve fore in density problems

When given 2 of them it makes it extremely easy to solve for the third

When trying to figure out which form of the density equation to use: cover up what you are looking for and the 2 units left and the sign between them shows you how to solve for it. EX 3-1: WHAT IS THE DENSITY OF AN OBJECT WITH A VOLUME OF 35.7 CM3 AND OF 85 g?

Bonus: Is this a solid, liquid, or not enough information to know? EX 3-2: IF THE DENSITY OF 19.3 g/cm3 WHAT IS THE VOLUME OF 200 g OF GOLD? EX 3-3: THE DENSITY OF LIQUID MERCURY IS 13.6 g/mL. HOW MUCH WOULD 35 mL OF MERCURY WEIGH (IN GRAMS AND POUNDS)? Hint: 1 pound = 453.59 grams EX 3-4: AN EMPTY GRADUATED CYLINDER WEIGHS 26.5 g. WHEN IT IS FILLED WITH AN UNKNOWN LIQUID TO THE 45.8 mL MARK THE NEW WEIGHT OF BOTH THE GRADUATED CYLINDER AND THE UNKNOWN LIQUID IS 70 g. WHAT IS THE DENSITY OF THE UNKNOWN LIQUID?

Hint: Put the differences in masses in your equation there should be a m1 and m2. EX 3-5: A RECTANGULAR SOLIDS HAS THE DIMENSIONS FOR 3.4” BY 1.2” BY1.7” AND WEIGHS 1,500Kg. WHAT IS THE DENSITY Hint:1 in3 = 2.54 cm3 DENSITY OF WATER

Memorize the specific density of water!!!!

1.0 g/mL

This means 1.0 gram of water has a volume of 1.0 mL and 1.0m mL of water 1.0 gram

This is only true at one temperature: 3.98º C

Substance that has a density less then water will float in it and ones with a heaver density will sink EX 3-6: HOW MUCH DOES 500mL OF WATER WEIGH IN GRAMS? 1.0 L? Hint: Use density of water to figure this one out EX 3-7: A CERTAIN SUBSTANCE HAS A MASS OF 3.2 kg AND A VOLUME OF 1.5 ft3. IF IT DOESN'T REACT WITH THE WATER, WOULD YOU EXPECT IT TO FLOAT OR SINK? Hint: Remember to convert all units to appropriate units 1 ft3 = 12 in3 1 in3 = 254 cm3 SPECIFIC GRAVITY

Specific Gravity: of a substance is the density of the substance compared to the density of a designated standard (water)

If you divide the specific gravity to our standard’s (water) density. You will get the same number as the specific gravity

Specific Gravity is unitless and Density has units EX 3-8: MILK HAS A SPECIFIC GRAVITY OF 1.12. HOW MUCH WOULD 1 GALLON OF MILK WEIGH IN GRAMS AND POUNDS? Hint: Convert Volume First 1 gal = 4 qt 1 L = 1.06 qt then mL to L Use specific gravity in density equation 1 lb = 454 g BRIEF HISTORY

Democritus- an ancient Greek, 400 B.C. He hypothesisxed that matter could be subdivided again and again until ir reaches particles that cannot divide. Other words, he was the first to suggest the existences of the atom.

John : first to develop and publish a theory about how look and behave. ’S

1. All elements are composed of small particles called atoms that are indivisible

2. All atoms of the same element are identical. (not true today because of Isotopes)

3. Atoms of different elements are different.

4. Atoms of different elements can combine with each other only in simple whole number ratios to form compounds

5. Chemical reactions occur when atoms are separated, joined or rearranged ERNEST RUTHERFORD

Gold Foil Experiment - the atom was mostly space and that all positive charges were located in a very small central nucleus

The Rutherford Gold Foil experiment shot minute particles at a thin sheet of gold. It was found that a small percentage of the particles were deflected, while a majority passed through the sheet. This caused Rutherford to conclude that the mass of an atom was concentrated at its center along with its .

https://youtu.be/5pZj0u_XMbc MORE HISTORY

Niels Bohr- A Danish scientist who was the first to suggest the “planetary model” of the atom. Meaning the orbited the nucleus like the planets orbit the sun.

Max Planck- A German Physicist who expanded and modified Bohr’s model. He theorized and proved with the quantum mechanical model that electrons do not actually “orbit” the nucleus but are found only in definite areas based on the amount of energy they have. This theory holds true today ATOMS

Atom- The smallest unit of matter that still retains the properties of an element

Each element consist of a certain type of atom different from the atoms of any other element (every type of atom is different)

Atoms make up all matter! SUBATOMIC PARTICLES

Atoms are made up of three types of particles containing a “charge”

Protons (+) These are found in the nucleus it is much larger then an

Electrons (-) These are found outside the nucleus in the what is called the “electron” cloud

Neutrons (neutral) these are found in the nucleus it is the same size as a but no charge. ELECTRONS

Electrons orient themselves around atoms in different levels called Electron Shells

The outer most shell is called the Valence Shell

The electrons on the outermost layer “Valence Shell” are called Valence Electrons SUBATOMIC PARTICLES

Most atoms are neutrally charged

# of Electrons = # of Protons

Protons and are packed densely in the middle or core of the atom this is called the

Electrons are located in the outer rings of the nucleus or electron cloud AND MASS

All atoms of the same element have the same number of protons in their nuclei

Atomic Number - the number of protons that is unique to an element it can also represent the number of electrons in a neutral atom

Atomic Mass - Average masses of all the isotopes of that particular element weighted by their percentage of abundance (the units are atomic mass units)

Mass Number - sum of the protons and neutrons in the nebulous WHEN USING ATOMIC MASS IN EQUATIONS:

Atomic Mass = (% 1)(mass of #1) + (% isotope2)(mass of #2) + etc.

Even though you are finding an average know that you do not divide by the number of isotopes.

You must either change your percentage to a decimal before putting them into your equation EX 3.9: NATURALLY OCCURRING IS 75.53% CHLORINE-35 AND 24.47% CHLORINE-37. WHAT IS THE AVERAGE ATOMIC MASS THAT SHOULD BE PLACED ON THE PERIODIC TABLE? EX 3-10: WHAT ARE THE ATOMIC #, ATOMIC MASS, PROTON #, & ELECTRON #? EX 3-11: WHAT ARE THE ATOMIC #, # OF PROTONS, AND # OF ELECTRONS FOR EACH OF THESE ELEMENTS?

Nitrogen (N)

Oxygen (O)

Neon (Ne)

Potassium (K) EX 3-12: NAME THE NEUTRAL ELEMENTS WITH THIS MANY PROTONS:

16

72

5

19

25 CHARGED PARTICLES

A non-neutral atom is called a charged particle. The particle can either be positively or negatively charged.

With charged particle you can only gain and loose electrons

If the particle is positively charged it has less electrons then protons and vise versa is you have a negatively charged particle

When writhing out an element that is charge you wright out the element as you would normally would then out beside it as an exponent wright the charge of the particle with a (-) for negative charges and a (+) for positive charges

Mg+2

C-1 EX 3-13: WHAT PARTICLE HAS A +2 CHARGE AND 12 PROTONS? EX 3-14: WHAT PARTICLE HAS A -3 CHARGE AND 33 PROTONS? How many electrons are in this charged particle? EX 3-15: WHAT PARTICLE HAS 50 PROTONS AND 48 ELECTRONS? ISOTOPE

All atoms of a given element have the same number of protons but some atoms have more neutrons then other atoms of the same element thus they have greater mass. These elements are called Isotopes

12C 13C

A Radioactive Isotope is one in which the nucleus days spontaneously giving off particles and energy TYPES OF BONDS

Bonding is how 2 or more 4 Types elements come together Covalent Bonds to form a compound Ionic Bonds Some bonds are stronger Bonds then others (ex: covalent Van der Waals bonds are much stronger Interactions then hydrogen bonds) STRONG VS. WEAK CHEMICAL BONDING

Strong Bonds: Weak Bonds:

Covalent Hydrogen

Ionic Van der Walls Interactions COVALENT BONDS

Covalent Bonds happen when valence electrons are being shared between 2 atoms equally

This is a very strong bond but the strength of the bonds are dictated by how many pairs of valence electrons are being shared

Single bonds have one pair of valance electrons being shared

Double bonds have 2 pairs of valance electrons being shared

Triple Bonds have 3 pairs of valance electrons being shared IONIC BONDS

Ionic bonds happen when there is unequal sharing of valance electrons

Because of unequal sharing one atom becomes more negative while the other atom becomes more positive

Ions- Charged atoms

Cation is the positively charged ion

Anion is the negatively charged ion

Ionic bonding must have both an anion and cation

HYDROGEN BONDING

Hydrogen bonds- When an is already bound to make a compound and it exerts an attraction on other elements or compounds

These bonds are individually weak but can add up and make many strong bonds VAN DER WAALS INTERACTIONS

These are interactions between compounds and their charge orientations (opposites attract)