Chem 1010 CH 6

If a neutral atom gains two electrons, what is the electrical charge of the atom?

-2

How many nonbonding pairs of electrons are in the following molecule? H-H

0 PAIRS

How many electrons are used to draw the electron-dot structure for acetylene?

10

How many electrons are used to draw the electron-dot structure for calcium chloride?

16

How many covalent bonds would the O atom usually form?

2

How many covalent bonds will the N atom usually form?

3

If the concentration of gold in seawater is 2.0 milligram per ton of sea water and the mass of the ocean is 1.5 × 1018 tons, how much gold is in the ocean?

3.0 × 1012 kg

How many substituents are on the carbon atom in CH_4?

4

How many substituents are on the nitrogen atom in N H 4 + ?

4

How many valence electrons does bromine (Br, atomic no. = 35) have?

7

If you mix a typical aluminum ion (Al, atomic no. = 13) with a typical oxygen ion (O, atomic no. = 8), what compound is formed?

Al2O3

Which of the following elements will most likely not form an ion at all?

Ar

An individual carbon-oxygen bond is polar. Yet carbon dioxide is nonpolar because ________.

B and C

What is the molecular shape of the water molecule?

BENT

If you mix a typical iodine ion (I, atomic no. = 53) with a typical barium ion (Ba, atomic no. = 56), what compound is formed?

Bal2

Which of the following bonds would be the most polar?

C-F

Which of the following compounds would be ionic?

CaCl2

Which of the following elements will most likely form an ion with a -1 charge?

Cl

Which shows atoms in order of increasing electronegativity.

Cs, Y, Ga, P, O, F

How do the electron-dot structures of elements in the same group in the periodic table compare with one another?

Elements of the same group have the same number of valence electrons.

Which of the following has the greatest number of nonbonding pairs of electrons?

F

Which of the following molecules contains a polar covalent bond?

H-F

Which of the following molecules would contain a dipole?

H-F

What is the compound that forms if you react potassium and sulfur?

K2S

Two liquids, A and B, have very different physical properties. A and B do not mix. A boils at 80°C and freezes at -30°C. B boils at 35°C and freezes at -100°C. Molecules of which are likely to have the largest dipole?

Molecule A

List the following bonds in order of increasing polarity:

N-N < N-O < N-F < H-F

Which of the following molecules has the highest boiling point?

NH3

Which of the following elements will most likely form an ion with a +1 charge?

Na

Take enough money away from your bank account and the bank will show a negative credit. Take an electron away from an atom, however, and the atom shows up positive. Explain.

Neutral atoms contain identically charged but oppositely signed protons and electrons. Removing one of the negative electrons results in an excess of positively charged protons.

Which of the following statements describes a polar molecule?

None of these statements describe polar molecules.

Which of the following elements has six valence electrons?

O

Which bond is most polar?

O-H

Which molecule is most polar?

O=C=S

Distinguish between a metal and a metal-containing compound.

Only one of these contains ionic bonds.

Phosphine is a covalent compound that contains phosphorus, P, and hydrogen, H. What is its chemical formula?

PH_3

Which would you expect to have a higher melting point: sodium chloride, NaCl, or aluminum oxide, Al2O3?

The aluminum oxide has a higher melting point because of the greater charges of the ions, and hence the greater force of attractions between them.

Which should be larger, the potassium atom, K, or the potassium ion, K⁺?

The potassium atom, K, with an additional shell of electrons is larger.

Which would you expect to have a higher melting point: sodium chloride, NaCl, or cesium chloride, CsCl? Why?

The sodium chloride has a higher melting point because its ions are smaller, which allows oppositely charged ions to get closer.

Atoms of metallic elements can form ionic bonds, but they are not very good at forming covalent bonds. Why?

They have a great tendency to lose electrons.

Ammonia is more polar than is borane because it ________.

all of the above

Which of the following would be an ion with a double positive charge?

an Mg atom that loses two electrons

Calcium fluoride, CaF2, is an example of ________.

an ionic compound

An atom loses an electron to another atom. Is this an example of a physical or chemical change?

chemical change involving the formation of ions

The principal source of an atom's electronegativity is the ________.

effective nuclear charge

What surrounds the sulfur atom in SF4?

four substituent fluorine atoms plus one lone pair of electrons

The number of nonbonding (lone) electron pairs in the ammonia molecule is ________.

one

The neon atom tends NOT to gain any additional electrons because ________.

there is no more room available in its outermost occupied shell

The number of nonbonding (lone) electron pairs in the water molecule is ________.

two

The acronym VSEPR stands for ________.

valence shell electron pair repulsion

When is the electronic geometry of a molecule not the same as its molecular shape?

when one or more of the substituents is a lone pair of electrons