Chapter 3

Question 1

covalent bond

Answer 1

formed when atoms share electrons

Question 2

molecule

Answer 2

collection of atoms

Question 3

chemical formula

Answer 3

symbols for elements in use with subscripts to indicate the number of atoms (CO2)

Question 4

structural formula

Answer 4

H-O-H (pictoral)

Question 5

space filling model

Answer 5

shows relative size of the atoms as well as their orientation

Question 6

ball and stick model

Answer 6

3D model using spheres and rods

Question 7

properties of molecules

Answer 7

1. melting point
2. hardness
3. electrical/thermal conductivity
4. solubility
5. electric charge
6. bond energy (amount of energy needed to break a bond)

Question 8

ionic bonding

Answer 8

happens between an atom that easily loses electrons and an atom that has a high affinity for electrons

Question 9

ionic compounds

Answer 9

formed when metals react with non-metals

Question 10

coulomb’s law

Answer 10

E = (2.31 x 10^-19 J . nm) (Q1Q2 / r)

E = units of joules
r = distance between ions in nanometers
Q1, Q2 are numerical ion charges

Question 11

bond length

Answer 11

distance between two atoms where the energy is lowest

Question 12

covalent bonding

Answer 12

sharing of electrons by nuclei

Question 13

polar covalent bond

Answer 13

unequal sharing of electrons between atoms in a molecule, results in a charge separation in the bond

Question 14

electronegativity

Answer 14

the ability of an atom in a molecule to attract shared electrons to itself

Question 15

Linus Pauling’s method of determining values of electronegativity

Answer 15

Expected H–X bond energy = ( H–H bond energy + X–X bond energy) / 2

Question 16

Change of actual and expected bond energies

Answer 16

Delta = (H–H)actual - (H–X)expected

If delta = 0 then the electronegativities are identical

Question 17

the electronegativity of ionic bonds is

Answer 17

1. large
2. has ionic character the more electronegative it gets

Question 18

the electronegativity of polar covalent bonds is

Answer 18

1. intermediate
2. polar covalent

Question 19

the electronegativity of covalent bonds is

Answer 19

1. zero
2. becomes equalized (no major difference in deltas)

Question 20

increasing in polarity / electronegativity (bond types)

Answer 20

1. covalent (smallest)
2. polar covalent (middle)
3. ionic (large, biggest energy delta)

Question 21

electron configuration of compounds

Answer 21

atoms in a stable compound have a noble gas configuration

Question 22

ionic compound

Answer 22

term for compounds in a solid state

Question 23

compounds of ionic molecules

Answer 23

chemical compounds are always electrically neutral

Question 24

sizes of ion

Answer 24

size influences the structure and stability of ionic solids

size is determined by measuring the distance between ion centers

Question 25

isoelectric ions

Answer 25

ions that contain the same number of electrons

Question 26

percent ionic character of a bond

Answer 26

(measured dipole moment of X--Y) / (calculated dipole moment of X^+Y^-) x 100%

Question 27

operational definition of ionic compounds

Answer 27

any compound that conducts an electric current when melted

Question 28

localized electron model

Answer 28

a molecule is composed of atoms that are bound together by sharing pairs of electrons using the atomic orbitals of the bound atoms 1. pairs of electrons localized on a specific atom are called lone pairs 2. electron pairs found in the space between the atoms are called bonding pairs

Question 29

lewis structures

Answer 29

shows how valence electrons are arranged among atoms in a molecule atoms achieving noble gas configurations are central to the formation of a stable compound