Question

1. an element is identified by its

a. atomic mass
c. number of neutrons
b. atomic number
d. average atomic mass

1. in a double - ring stand set - up, what is the purpose of the top ring?

a. to keep the hot beaker from falling off the wire gauze while stirring.
b. to keep the wire gauze on the bottom ring.
c. to know how high to fill the beaker with chemicals.
d. to show where beaker tongs should lift the beaker from the wire gauze.

1. name the compound cf₄.

a. calcium fluoride
c. carbon fluoride
b. carbon tetrafluoride
d. monocarbon quadrafluoride

1. which of the following atoms has the highest ionization energy: cl, f, mg, fe

a. cl
c. mg
b. f
d. fe
for each of the next three questions, decide if the chemicals are polar, nonpolar, or ionic. (use only once)

1. chemical: o₂

a. nonpolar
c. ionic
b. polar

1. chemical: nf₃

a. nonpolar
c. ionic
b. polar

1. chemical: nacl

a. nonpolar
c. ionic
b. polar

1. balance the following equation and identify the coefficient of oxygen that will balance the following equation?

c₄h₁₀(g) + o₂(g) → co₂(g) + h₂o(g)
a. 12
c. 15
b. 13
d. 19

1. the energy required to remove an electron from an atom is the atoms...

a. electron affinity.
c. electronegativity.
b. electron energy.
d. ionization energy.

Explanation:

1. Q63: The atomic number equals the number of protons, which uniquely defines an element.
2. Q64: The top ring of a double ring stand secures the hot beaker on the gauze while stirring to prevent spills/breakage.
3. Q65: Use IUPAC naming for covalent compounds: prefixes indicate atom count, so 4 fluorine atoms use "tetra-".
4. Q66: Ionization energy increases up and right on the periodic table; fluorine is the top-rightmost atom here.
5. Q67: $O_2$ has a nonpolar covalent bond with equal electron sharing between identical oxygen atoms.
6. Q68: $NF_3$ has a trigonal pyramidal geometry, creating a net dipole moment from unequal N-F electron sharing.
7. Q69: NaCl forms from electron transfer between a metal (Na) and nonmetal (Cl), creating ionic bonds.
8. Q70: Balance the equation by first balancing C and H, then O: $2\text{C}_4\text{H}_{10} +13\text{O}_2

ightarrow 8\text{CO}_2 +10\text{H}_2\text{O}$.

1. Q71: Ionization energy is defined as the energy needed to remove a valence electron from a neutral atom.

Answer:

1. b. atomic number
2. a. To keep the hot beaker from falling off the wire gauze while stirring.
3. b. carbon tetrafluoride
4. b. F
5. a. Nonpolar
6. b. Polar
7. c. Ionic
8. b. 13
9. d. Ionization energy.