Unit 3: Models of Bonding and Structure

Question 1

Explain a Cation.

Answer 1

A metal loses an electron to form a positive ion.

Question 2

Explain an anion.

Answer 2

A non-metal gains an electron to form a negative ion

Question 3

Whats the difference in the nuclear charge on valence electrons in metals and non-metals

Answer 3

The valence electrons of metal atoms experience a smaller nuclear effective charge than non-metals

Question 4

What is the trend in Nuclear effective charge?

Answer 4

Its increases with the group number of the element . Increases across a period but remains approximately down a group.

Question 5

Why do metals form cations?

Answer 5

Because they have first ionization energy.

Question 6

Why are the noble gases unreactive?

Answer 6

The high ionization energies and complete energy levels.

Question 7

What structure do ionic compounds have?

Answer 7

A lattice structure, pulled together by electrostatic attraction.

Question 8

Describe the characteristics of ionic compounds.

Answer 8

• They have high melting and boiling points and low volatility (the tendency of a substance to vaporize)
• They have high electrical conductivity in the liquid and aqueous state
• Brittle

Question 9

What does it mean when molecules are hydrated?

Answer 9

The molecules have been dissolved in water. The attraction to the partial charges pools the lattice apart and they become surrounded by water molecules.

Question 10

What does it mean when molecules are solvated?

Answer 10

The molecules have been dissolved into something other then war and have been surround by the solvents molecules.

Question 11

When do ionic compounds conduct electricity?

Answer 11

When they are in the liquid or molten state. Not in the solid state.

Question 12

How do covalent bonds form?

Answer 12

By two non-metals sharing electrons

Question 13

What does the octet rule refer to?

Answer 13

The tendency of atoms to gain a valence shell with a total of eight electrons.

Question 14

How many electrons and pairs in a double bond

Answer 14

Two electron pairs and four electrons.

Question 15

How many electrons and pairs in a triple bond

Answer 15

Three electron pairs and six electrons

Question 16

What is a coordination bond?

Answer 16

A bond in which both shared electrons come from the atom

Question 17

Whats a ligand?

Answer 17

An atom that donates a pair of electrons to the central atom.

Question 18

What shape does a molecule with two electron domains take?

Answer 18

Linear (180)

Question 19

What shape does a molecule with three electron domains take?

Answer 19

Triangular planar (120)

Question 20

What shape does a molecule with 3 electron domains, 2 bonding and 1 lone pair, create

Answer 20

Bent or v-shaped

Question 21

What shape does a molecule with 4 electron domains take?

Answer 21

Tetrahedral (109.5)

Question 22

What shape does a molecule with 4 electron domains take? (1 lone pair, 3 bonding)

Answer 22

Trigonal pyramidal. (107)

Question 23

What shape does a molecule with 4 electron domains take? ( 2 lone pairs, 2 bonded)

Answer 23

Tetrahedral bent (104.5)

Question 24

What is an allotrope?

Answer 24

Elements that have different bonding and structural patterns of the same element in the same physical state and so have different chemical and physical properties.

Question 25

What causes an induced dipole?

Answer 25

The electron cloud is mobile and they density of this cloud may change to be grater then one atoms resulting in an instantaneous difference of charge.

Question 26

When do London dispersion forces occur?

Answer 26

All the time due to the weak force of attraction caused by induced dipoles.

Question 27

When do atoms have dipole-dipole attraction

Answer 27

When a compound has a permanent electronegativity difference known as a permanent dipole and attracting each other generating a force.

Question 28

When does dipole induced-dipole attraction force occur?

Answer 28

When a mixture contains both polar and non polar molecules, the permanent dipole of a polar molecule can cause temporary separation of charge on a non polar molecule.

Question 29

What do van der Waals forces refer to

Answer 29

All intermolecular forces that do not involve electrostatic attraction between ions.

Question 30

What shape does a molecule with 5 electron domains take? (all bonding)

Answer 30

Triangular bipyramidal (90, 120)

Question 30

When does hydrogen bonding occur?

Answer 30

Between molecules in which hydrogen is bonded to fluorine nitrogen or oxygen.

Question 30

What shape does a molecule with 5 electron domains take? ( 1 lone pair)

Answer 30

See saw ( <120, <90)

Question 31

What shape does a molecule with 4 electron domains take? (2 bonding)

Answer 31

T-shaped (<90)

Question 32

How does a sigma bond form?

Answer 32

When two atomic orbitals combine head on along the bond axis, the electron density is concentrated between the nuclei of the bonded atoms.

Question 32

What shape does a molecule with 4 electron domains take? ( 3 lone pairs)

Answer 32

Linear (180)

Question 32

What shape does a molecule with 6 electron domains take? (all bonding)

Answer 32

Octahedral (90)

Question 33

What shape does a molecule with 6 electron domains take? (1 lone pair)

Answer 33

Square pyramidal (<90)

Question 34

What shape does a molecule with 6 electron domains take? (2 lone pairs)

Answer 34

Square planar (90)

Question 35

How does a pi bond form?

Answer 35

When two p orbitals combine laterally, the electron density in concentrated above and below the bond axis

Question 36

Where does metallic bonding occur?

Answer 36

The electrostatic attraction between a lattice of cations and delocalized electrons.

Question 36

Explain why an element has good electrical conductivity.

Answer 36

Delocalized electrons are highly mobile, and so can move through the metal structure in response to an applied voltage.

Question 37

Explain why an element has good thermal conductivity.

Answer 37

Delocalized electrons and closely packed ion enable efficient transfer of thermal energy.

Question 38

Explain why metals are malleable

Answer 38

The movement of delocalized electrons is non-directional and random so the bond remains intact under pressure.

Question 39

Explain why metals have high melting points.

Answer 39

A lot of energy is required to overcome the strong electrostatic forces of attraction in the metallic bond and separate the atoms.

Question 40

Explain why metals are lustrous.

Answer 40

Delocalized electrons in metal crystal structure reflect light.

Question 41

What does the strength of a metallic bond depends on the charge and the radius of the metal ions

Answer 41

- The number of delocalized electrons - The charge on the cation - The radius of the cation