Structure 2 - Models of bonding and structure

Question 1

Why is a metallic bond non-directional?

Answer 1

Electrons shared with every cation

Question 2

Lattice

Answer 2

3D repeating structure

Question 3

Properties of metals

Answer 3

Good thermal and electrical conductors
melleable
strength

Question 4

Can two metals bond together?

Answer 4

Yes but most likely through an alloy (multiple metals). Brass contains copper and zinc

Question 5

Ionic bond

Answer 5

A strong electrostatic attraction between positive and negative ions

Question 6

Binary ionic compound

Answer 6

A binary ionic compound is composed of ions of two different elements like sodium iodide and sodium chloride. A non binary ionic bond is NaNO₃.

Question 7

Monatomic ion

Answer 7

A monatomic ion is a ion that consists of only one atom “Monobrow”

Question 8

Polyatomic ion

Answer 8

A polyatomic ion is an ion that consists of two or more atoms such as sulphate.

Question 9

Ionic lattice

Answer 9

An ionic lattice is a regular repeating structure consisting of alternating cations and anions. Also 3D.

Question 10

Bonding of ionic compound

Answer 10

Electrostatic attraction between cations and anions. Ionic bond

Question 11

Characteristics of ionic bonding

Answer 11

Not volatile
Soluble in water
Brittle

Question 12

Covalent bond

Answer 12

Bonds form to form a stable electron configuration and release energy. Electrons are shared

Question 13

Octet rule

Answer 13

Tendency of atoms to prefer to have 8 electrons in the valence shell

Question 14

What is the duplet rule and what elements does it apply to?

Answer 14

Same as octet rule except it’s a tendency to have 2 electrons in valence shell. This applies to hydrogen

Question 15

Difference between lone pair and bonding pair of electrons?

Answer 15

Lone pair - not bonded to another element
Bonded pair - bonded to another element

Question 16

Sigma bond

Answer 16

Caused by direct overlap of two orbitals and is stronger than pi bonds. Every covalent bond has a sigma bond.

Question 17

Pi bond

Answer 17

Caused by sideways overlap of two orbitals and is much weaker than sigma bonds.

Question 18

Coordination bond

Answer 18

Both electrons shared from same atom. Often shown by an arrow pointing from the atom which donates the lone pair to the atom which receives it.

Question 19

Resonance

Answer 19

Molecule or polyatomic ion for which two possible Lewis formula’s can be drawn.

Question 20

Resonance hybrid

Answer 20

More stable than Lewis structures and is when more than two possible Lewis structures.

Question 21

Electronegativity

Answer 21

Ability of an atom to attract a bonding pair of electrons in a covalent bond.

Question 22

Dipole moment

Answer 22

Measure of net polarity which is the magnitude of charge at either end of the molecular dipole times the distance between charges.

Question 23

London forces

Answer 23

• Exist in all molecules
• May also be known as dispersion forces or instantaneous induced dipole-dipole forces

More info in revision book

Question 24

What affects the magnitude of London forces?

Answer 24

1. Number of electrons
2. Size of electron cloud
3. Shapes of molecules

Question 25

Dipole-Dipole forces

Answer 25

Electrostatic attraction between positive permanent dipole on one molecule to a negative dipole on an adjacent molecule. Created by a difference in electronegativity

Question 26

Hydrogen bonding

Answer 26

An attractive interaction between hydrogen and another atom which has a higher electronegativity than hydrogen such as fluorine, nitrogen and oxygen.

Question 27

Two types of electrostatic forces

Answer 27

Intramolecular - inside molecules Intermolecular - between molecules

Question 28

Strongest to weakest intermolecular bonds

Answer 28

Hydrogen bonding - strongest Dipole-Dipole London forces - weakest

Question 29

Electron geometry

Answer 29

Shape of all electron domains

Question 30

Molecular geometry

Answer 30

Shape formed by just the atoms in a molecule

Question 31

What structure will form with just 2 electron domains?

Answer 31

0 lone pairs = Linear - bond angle 180 degrees

Question 32

What structure will form with just 3 electron domains?

Answer 32

0 lone pairs = Trigonal planar - bond angle 120 degrees 1 lone pair = Bent - bond angle - bond angle 117 degrees

Question 33

What structure will form with 4 electron domains?

Answer 33

0 lone pairs = Tetrahedral - bond angle 109.5 degrees 1 lone pair = Trigonal pyrimidal - bond angle 107 degrees 2 lone pairs = Bent - bond angle 104.5 degrees

Question 34

What structure will form with 5 electron domains?

Answer 34

0 lone pairs = Trigonal bipyrimidal - bond angle 90 and 120 degrees 1 lone pair = sawhorse - bond angle 120 degrees

Question 35

What structure will form with 6 electron domains?

Answer 35

0 lone pairs = Octahedral - bond angle 90 degrees

Question 36

Ligand

Answer 36

Molecule that can donate a pair of electrons such as H2O. They attach to a transition metal.

Question 37

Formal charge formula

Answer 37

Formal charge (No. of valence electrons) - ((No. of non-bonded electrons) + 1/2 (No. of bonded electrons))

Question 38

What does the formal charge formula determine?

Answer 38

Used to determine the correct Lewis structure

Question 39

What is hybridisation?

Answer 39

the process of combining two atomic orbitals to create a new type of hybridised orbitals. sp3 - 4 hybrid orbitals - tetrahedral, 109.5 degrees sp2 - 3 hybrid orbitals - trigonal planar, 120 degrees sp - 2 hybrid orbitals - linear, 180 degrees amount of hybrid orbitals = amount of electron domains

Question 40

Limitations of the van arkel-ketelaar triangle

Answer 40

Doesn't work for more than two elements Doesn't take into account differences in structure meaning for example it suggests all allotropes of carbon have the same melting point