1. Chemistry Review sheet
Answer Key

2. Numbers 1-7
1. Atoms are made of ______PROTONS___ (+), ____NEUTRONS___ (neutral), and ___ELECTRONS_____ (-).
2. PROTONS______ and ____NEUTRONS____ are in the nucleus of the atom and when added together they give you the ____ATOMIC MASS______ of the atom.
3. __ELECTRONS___ move quickly and constantly around the outside of the nucleus in the __ELECTRON__ __SHELL___.
4. The number of __ELECTRONS____ can change which forms ______IONS____ ( + or -).
5. Atoms of the same element will ALWAYS have the same number of ___PROTONS___ or atomic ___NUMBER_____.
6. We call atoms of the same elements with different numbers of neutrons ____ISOTOPES_______.
7. Elements are classified as _____METALS___, _____NON_METALS______, or ____METALLOIDS____.

3. Numbers 8-10
8. Metals are on the __LEFT___ and ___CENTER____ of the periodic table. They tend to be:
a. Malleable: EASILY BENT/ROLLED INTO SHEETS
b. Conductive: ABLE TO MOVE ELECTRICITY
c. usually a ____SOLID__ at room temperature
9. Metalloids are found along the __STAIR- STEPS____ on the periodic table.
10. Non- Metals are found on the _____RIGHT_____ side of the periodic table. They tend to be poor conductors. Many are _______GASES________ at room temperature.

4. 11-16 11. a-ATOMIC NUMBER B. ATOMIC SYMBOL C. ATOMIC NAME
D. ATMOIC MASS
12. How many protons does Potassium have? 19
13. How many electrons does Sulfur have? 16
14. How many neutrons does Potassium have? 20
15. How many electrons would Potassium (+1) have? 18
16. How many protons would Sulfur (-1) have? 16

5. 17-21 C12H6O6 17. How many oxygen atoms are in the molecule above? 6
18. How many carbon atoms are in the molecule above? 12
19. How is the periodic table organized? BY INCREASING ATOMIC NUMBER.
20. The rows in the periodic table are called ____PERIODS____. They are organized by ______INCREASING ATOMIC NUMBER__________.
21. The columns in the periodic table are called _____FAMILY/GROUPS____. They are grouped by _________SIMILAR PROPERTIES/REACTIVITY____________.

6. 22-26
22. Most of the elements on the periodic table are ____METALS____.
23. Matter is anything that takes up ___SPACE__ and has __MASS_____. All matter is made of __ATOMS___.
24. Some elements are turned into electrical wires. Which properties (from above) must they have to be used in this way? Explain why.
CONDUCTIVITY- BECAUSE WIRES NEED TO BE ABLE TO
25. __DENSITY_ can be found by dividing the mass of an object by its volume.
26. What is solubility? ABILITY FOR A SOLUTE TO DISSOLVE INTO A SOLVENT

7. 27. Identify the following atoms:
A. ____CARBON__ B. ____OXYGEN__ C. ________LITHIUM______

8. PURE SUBSTANCES
PURE SUBSTANCES:
___ELEMENTS____are pure substances that cannot be changed into simpler substances.
Elements are composed of ________ONE_____ kind of atom.
_____COMPOUNDS____ are pure substances that are composed of _______2 OR MORE________types of elements that are chemically combined.
Compounds can only be changed into simpler substances called elements through _______CHEMICAL CHANGES________________
MIXTURES
Mixtures are ______PHYSICAL_______ combinations of two or more different substances that retain their own individual properties and are combined physically (mixed together).
Mixtures can be separated by physical means (____FILTRATION____, ____SIFTING_____, ____EVAPORATION____)
Characteristic properties can be used to identify different materials and to separate a mixture into its components.

9. MIXTURES Mixtures may be heterogeneous or homogeneous.
§ In a ______HETEROGENEUS______ mixture, which is not uniform throughout, the component substances can be visibly distinguished. Tossed salad, granite, and iced tea are examples of heterogeneous mixtures.
§ In a _____HOMOGENEOUS_________mixture, which is uniform throughout, the substances are evenly mixed and cannot be visibly distinguished. Air, steel, clear salt-water are examples of homogeneous mixtures.

10. ECM DIAGRAMS
1. c
2. e
3. b
4. a
5. d

11. SLG What causes a change in state? Change in thermal energy
Which phase is most dense? solid
Which phase is least dense? gas
Solid: definite shape and volume,
Liquid: no definite shape, definite volume
Gas: no definite shape or volume- particles bounce around.

12. Chemical and Physical Properties
____PHYSICAL______ properties can be observed and measured without changing the kind of matter being studied.
Physical properties include: shape, density, solubility, odor, ___MELTING____ point, ___BOILING____ point, and color
______CHEMICAL______ properties can be recognized only when substances react or do not react chemically with one another, that is, when they undergo a change in composition..
Chemical properties include: acidity, basicity, combustibility, and ____REACTIVITY________.
Chemical and Physical properties can be used to ______DETERMINE_______ a substance by comparing the properties of the substance to unknown substances.

13. Chemical and Physical Changes
_______PHYSCIAL______changes do not change the composition of a substance, only the physical properties.
Change in ________STATE_____ of matter
Change in ______SHAPE___ or _______SIZE__________
_______CHEMICAL__________ changes result in the formation of one or more new substances with new chemical and physical properties.
The four types of evidence that show a chemical change/reaction has occurred are a change in _____COLOR____, a change in ___TEMP____, formation of a __GAS__, or formation of a ___PRECIPITATE________.
reactions occur at different rates, slow to fast, and that reaction rates can be changed by changing the ____CONCENTRATION____ of reactants, the ____TEMPERATURE___, the surface areas of solids, and by using a catalyst.
solutions can be acidic, basic, or neutral. The pH scale is used to classify solutions. Neutral solutions have a pH of 7. Acids have a pH of ______LESS___ than 7. Bases have a pH of ______MORE____ than 7.

14. CHEMICAL OR PHYSICAL CHANGE?
Look at each example below. If the change is chemical, write a C, if it is physical, write a P
__P_ Ice cream melts __P_ Water evaporates _C__ Iron Rusts _C__ Apple browns in air
__P_ sugar dissolves __C_ wood burns to ash __P_ paper is wrinkled __C_ vinegar/baking soda bubble
__P__ water boils __P_ Ice melts __P_ metal is dented
__P__ sublimation

15. CHEMICAL FORMULAS CHEMICAL FORMULAS AND BALANCING EQUATIONS:
A ___CHEMICAL EQUATION_______can be used to represent a chemical reaction that has occurred.
An _____ARROW_____is used to distinguish between the substance that are broken apart or combined, and can be understood as meaning “yields” or “makes”.
____REACTANTS____are the substances broken apart or combined in a chemical reaction and that they are located on the left side of the arrow in a chemical equation. o
_______PRODUCTS__________are new substances formed in a chemical reaction and that they are located on the right side of the arrow in a chemical equation.
Label each part of the chemical equation:
2H O > H20.
_______REACTANTS______ __________PRODUCTS______

16. LAW OF CONSERVATION OF MASS
When materials _____REACT___ with each other, many changes can take place, but that in every case the total amount of matter ____BEFORE_____ is the same as _____AFTER_____.
balanced chemical equation supports the law of conservation of matter.
What does the Law of conservation of Matters state?
THE AMOUNT OF MATTER STAYS CONSTANT- MEANING WHAT GOES INTO AN EQUATION MUST EQUAL WHAT COMES OUT OF AN EQUATION.

17. QUESTIONS 28 AND 29 4 GRAMS REACTANTS= 2+2 PRODUCT = 4
28. Balance the following reaction:
__2__NaCl ____I > __2__ NaI ____Cl2
30. 2 grams of sodium are mixed with 2 grams of chlorine. They undergo a chemical reaction. What is the mass of the product, sodium chloride?
4 GRAMS
REACTANTS= 2+2 PRODUCT = 4
REACTANTS AND PRODUCTS MUST BE EQUAL