1. Semester Exam Review
Foothill Chemistry

2. Basic Chemistry Definitions
Element - substance that cannot be changed into simpler substances by chemical means
Compound - substance composed of two or more substances chemically combined in a fixed proportion
Mixture - a physical blend of two or more components
Homogeneous Mixture - describes mixture with a uniform composition
Heterogeneous Mixture – describes mixture with a non-uniform composition
Phase - part of a sample having uniform composition and properties

3. More Basic Chemistry
Chemical Reaction - process in which substances are changed into different substances
Reactant - starting substance in a chemical reaction
Product - a substance formed in a chemical reaction
Vapor - gaseous state of substance that is a liquid or solid at room temperature
Distillation - a process in which a liquid is boiled to produce a vapor that is condensed again into a liquid

4. Atoms
Atom - the smallest particle of an element that retains the properties of that element
Mass - amount of matter an object contains
Proton – positively charged subatomic particle
Electron – negatively charged subatomic particle
Neutron – subatomic particle with no charge
Nucleus - the central part of an atom, containing protons and neutrons

5. Mass Mass Number – Protons + Neutrons
Atomic Mass Unit – 1/12 of carbon-12 mass
Atomic Mass – Weighted average mass of the atoms in a naturally occurring sample of an element
Molar Mass – Mass of one mole of a substance in grams

6. Isotope Notation (Element Symbol) 1H 1H 12C 6C 13C 6C 14C 6C
Mass Number
Charge
(Element Symbol)
Atomic Number 1H 1H
12C 6C
13C 6C
14C 6C
Atomic Number = Number of Protons in an atom (the element # on the Periodic Table)
Mass Number = Number of Protons + Number of Neutrons in an atom
Charge = Number of Protons – Number of Electrons in an atom
Isotope - atoms with the same number of protons, but different numbers of neutrons in the nucleus of an atom

7. Ionic Compound
Formed by the attraction of oppositely charged ions (Usually between Metal and Non-Metal)
High melting point
Called Salts
Total of positive and negative charged ions must = 0

8. Covalent Compound Formed when elements share electrons
Shared electrons are found in between the two elements
Usually between two or more non-metals
Also called molecular compounds
Naming uses the mono-, di-, tri-, etc. prefixes

9. Significant Figures
Multiplication – Smallest number of significant figures of all the terms
Addition – Smallest number of digits after the decimal point of all the terms
Left zeroes are not significant.
Right zeroes before the decimal point are not significant unless there is a decimal point
Right zeroes after the decimal point are significant
Zeroes in the middle are significant

10. Ions Cation – Positive Ion Anion – Negative Ion
Roman numeral gives the charge
-ic suffix higher charge number / - ous lower charge number
Anion – Negative Ion
Monoatomic anions – end in –ide
Make hydro[root]ic acids
Polyatomic anions – end in –ite or –ate
-ate ions have more oxygen than –ite ions
-ite makes [root]ous acids
-ate makes [root]ic acids

11. Hard Test Question
What is the energy of a microwave photon that has a frequency of 1.12 x 1012 Hz? (h = 6.63 x 10-34Js) ?
Make sure that your answer includes the correct number of significant figures and the correct units. Show your work for full credit.

12. Essay Questions
Positive ions are smaller than the atoms from which they are formed, but negative ions are larger than the atoms from which they are formed. Explain why this is so.
Explain how atoms (ions) are held together in an ionic bond. Give an example of an ionic compound.
Explain what a polar molecule is. Provide an example.
Explain the difference between chemical properties and physical properties. Give an example of each.

13. Other things to know Atomic Mass Calculation Formula Mass Calculation
Molecular Mass Calculation
Percent Composition Calculation
Electron Configuration (Aufbau Diagram)
Representative Elements = Group A Elements
Valence Electron Determination