UNIT 1 & 2 Review

First Quarter Exam Material

Periodic Table

The Periodic Table of Elements shows all of the known elements, arranged by Increasing atomic number

The Atom

The smallest particle of an Element is an Atom

To the right are the atoms in the Element Gold

http://www.chem.utoronto.ca/staff/DHIRANI/stm-np.jpg

Atomic Models

Democritus Basic shapes to identify “atoms” No subatomic particles

Atomic Models

Dalton Invisible and Indivisible No subatomic particles

Atomic Models

Thomson Plum Pudding Positive substance containing negative

particles

Atomic Models

Rutherford Protons in Nucleus Electrons around Nucleus

Atomic Models

Bohr Protons and Neutrons in Nucleus Electrons around Nucleus in Orbits

N

Atomic Models

Electron Cloud Protons and Neutrons in Nucleus Electrons around Nucleus in a cloud

formed my probability

N

Subatomic Particles

Particle Charge Mass Location

Proton + 1 1 amu nucleus

Neutron 0 1 amu nucleus

Electron - 1 0 Outside the nucleus

Isotope

An Isotope is an atom with the same number of protons, but a different number of neutrons. Changing the neutrons changes the mass of the atom.

Isotope Examples

Carbon-13 and Carbon-12The 13 and the 12 represent

different masses for each atom. The “-” is a dash, not a negative sign.

13C and12C are also ways to indicate different masses

Protons

Atomic number = # Protons

Carbon has 6 Protons

Electrons

Atomic number = # Electrons Unless there is a charge

Fluorine has 9 electrons F-1 has 10 electrons Sodium has 11 electrons Na+1 has 10 electrons

Neutrons Atomic mass - # protons = # neutrons

Carbon-12 (mass)12 – (protons)6 = 6 neutrons

Carbon-13 (mass)13 – (protons)6 = 7 neutrons

Drawing Bohr Models Protons and Neutrons in

nucleus Electrons in rings outside of

nucleus

Ring 1 = 2 electronsRing 2 = 8 electronsRing 3 = 8 electronsRing 4 = 18 electronsRing 5 = 18 electronsRing 6 = 32 electronsRing 7 = 32 electrons

Chemical Formulas

Represents the number of each type of element bonded together in a compound

Remember to Multiply when there are parenthases

Calcium Phosphate, Ca3(PO4)2

Ca-3, P-2, O-8

13 total atoms in one molecule of the compound.

Kinetic Theory

Kinetic Theory states that atoms and molecules are in constant Motion

Phase Changes Point C = Boiling

from Liquid to Gas

Point B = Liquid Form

Point A = Melting from Solid to Liquid

The plateau (flat part of the graph) represents the phase change. The temperature of the substance does not rise (or fall) until all of it has changed phases

Time

Tem

pera

ture

A

B

C

Moles Amedeo Avagadro came up

with the “Chemist’s Dozen” 1 mole contains 6.02 x 1023

Particles

Mole Continued

The mass of one mole of any element is the same as the molar mass. Example: 1 mole of C = 12.011 grams

This means that 6.02 x 1023 atoms of Carbon has a mass of 12.011 grams.

Sig Figs Placeholders are NOT significant

figures. With Addition/Subtraction line up the

decimals. With Multiplication/Division the

number of sig figs is based on the number that has the least number of sig figs.

Refer to the sig fig worksheet for complete rules.

Answers to sig fig problems Determine the number of significant figures in each

measurement. 508.0 L ________4____________ 0.008204 g_________4___________

Round all numbers to four significant figures. Write the answers to e-h in scientific notation.

847950 kg ___847900_________ 38.5421 g____38.54__________

Complete the following addition and subtraction problems. Round off the answers when necessary

43.62 + 51.0 + 8.73 = ______103.3_________ 258.3 - 257.11 =_____1.2__________

Complete the following calculations. Round off the answers to the correct number of significant figures.

24 x 3.25 = _____78__________ 120 / 10 = ________10__________

Density

Density is a ratio of mass and volume. How tightly packed?

D = Density = Mass Volume

Separating Mixtures

In the separating mixtures lab the four methods of separation were listed. Filtration Decanting Evaporation Distillation

Mixtures

A Heterogeneous mixture is one where the different parts can be easily seen.

o A Homogeneous mixture is one where the particles are mixed so well that the separate parts cannot be seen.

Saturated vs Unsaturated

Saturated: Contains the maximum amount of dissolved solute for a given amount of solvent at a specific temperature and pressure.

• Unsaturated: Contains less dissolved solute for a given temperature and pressure than a saturated solution; has further capacity to hold more solute.

Changes

A Chemical change occurs when atoms interact and rearrange to form new substance.

A Physical change occurs when properties of the substance changes, but the identity of the substance does not change.

Making and Breaking Bonds

When a bond is broken energy is required.

When a bond is made energy is released.