Unit 2 Review
1. Name 4 scientists that had early models of the atom. Describe their model.
Scientist
Democritus
Dalton
Thomson
Rutherford
Bohr
Chadwick
Electron Cloud
Significance
Atoms are the smallest piece of
matter. Cannot divide matter
forever.
Atoms are tiny solid balls. Atomic
theory put forth 4 big ideas of
matter.
Discovered the electron using his
cathode ray experiment. Plum
pudding model.
Atom is mostly empty space with a
dense nucleus at the center. Gold
Foil experiment.
Electrons orbit the nucleus in energy
levels. Planetary model.
Discovered the neutron.
Electrons travel around the nucleus
on random paths in an electron
cloud. Currently accepted model.
2.
Name the 3 parts of the atom. Describe each part.
Protons- positive, in nucleus, heavy; neutrons- neutral, in nucleus, heavy; electronsnegative, surround the nucleus, light
3. Give the atomic number, atomic mass, number of protons, number of neutrons and
number of electrons for each of these 4 elements: Carbon, Magnesium, Neon,
Hydrogen
C: 6, 12.001, 6 p, 6 n, 6e
Mg: 12, 24.30, 12 p, 12 n, 12 e
Ne: 10, 20.17, 10 p, 10 n, 10 e
H: 1, 1.007, 1 p, 0 n, 1 e
4. Give the definition and an example of these 4 terms: Isotope, Ion, Cation, Anion
Isotope- form of the element with a different number of neutrons, exp. Carbon-14
Ion- form of the element with a different number of electrons than protons, has a
charge, example Na+1
Cation- positive ion, has lost electrons, example Na+1
Anion- negative ion, has gained electrons, example Cl-1
Unit 2 Review
5. Name 3 trends (similarities or differences) that you see as you move across a period
(row).
Number of valence electrons increases, number of electron shells stays the same,
number of protons increases, size of element decreases
6. Name 3 trends (similarities or differences) that you see as you move down a group
(column).
Size of element increases, number of electron shells increases, number of valence
electrons stays the same
7. Give 4 characteristics of a metal.
Luster, good conductors, found on left side of table, dense, loses electrons during ionic
bonding, solid at room temp, malleable, ductile
8. Give 4 characteristics of a nonmetal.
Dull, brittle, not good conductors, can be solid/liquid/gas at room temp
9. Give 2 characteristics of a metalloid.
Can be semiconductors, characteristics of both a metal and nonmetal
10. Give 2 characteristics of a noble gas.
Does not like to bond (inert), gas at room temp, full outer shell
11. Name 3 metals.
Sodium, calcium, potassium, magnesium, lithium
12.Name 3 nonmetals.
Chlorine, fluorine, oxygen, hydrogen
13.Name 3 metalloids.
Boron, silicon, aluminum
14.Name 3 noble gases.
Krypton, argon, neon, helium
15.Give 3 pieces of information about an ionic bond.
Normally between metal and nonmetal, electrons are transferred, produces ions
16.Give two examples of an ionic compound. Identify the positive and negative ion in each
example.
NaCl- sodium becomes a positive cation, chlorine becomes a negative anion
LiF- lithium becomes a positive cation, fluorine becomes a negative anion
MgCl2- magnesium becomes a positive cation, chlorine becomes a negative anion
17.Give 3 pieces of information about a covalent bond.
Electrons are shared, between two nonmetals, no ions are formed
18.Give two examples of a covalent molecule.
H2, CO2, H2O, N2
Unit 2 Review
19.Tell how many valence electrons the following atoms would need to gain/lose in order
to fulfill the octet rule: Flourine, Sulfur, Sodium, Magnesium, Helium
F- gain 1
S- gain 2
Na- lose 1
Mg- lose 2
He- already full, doesn’t like to bond
20. Give three examples of molecules. (multiple atoms bonded together)
H2, CO2, H2O, N2
21.Name three examples of compounds. (multiple elements bonded together)
CO2, H2O, NH3
22.Explain the law of conservation of mass.
Matter cannot be created or destroyed, can only change form. Must have balanced
chemical reactions with the same number and types of atoms on either side of the
equation.
23.Give two examples of heterogeneous mixtures. Give two examples of homogeneous
mixtures.
Heterogeneous mixture- trail mix, salad dressing, chocolate chip ice cream
Homogeneous mixture- koolaid, salt water, shampoo
24.Name 5 physical properties.
Density, luster, taste, color, melting point, boiling point, solubility
25.Name 2 chemical properties.
Reactivity, flammability, combustibility
26.Give 2 signs that a chemical reaction has occurred.
Change in temp, light, new substance formed, gas is given off, change in odor
27.Give 3 examples of a physical change.
Phase change, change in size, dissolving
28.Give 3 examples of a chemical change.
Burning paper, milk spoils, vinegar and baking soda react
29.Name the 4 states of matter. Give two characteristics of each.
Solid, liquid, gas, plasma – see chart in notes
30.Name and describe what is happening at each of these five phase changes: evaporation,
melting, sublimation, condensation, freezing.
Evaporation- liquid to gas
Melting- solid to liquid
Sublimation- solid to gas
Unit 2 Review
Condensation- gas to liquid
Freezing- liquid to solid
31.Write the formula for density. Is density a chemical or physical property of matter?
Density= mass divided by volume
Is a physical property