Bonding

Question 1

What are the 3 main bonding types?

Answer 1

Metallic
-metals bonding together

Ionic
-transfer of e to form positive and negative ions
-metals and non-metals

Covalent
-electrons are shared (attraction)
-non-metals

Question 2

What is a valency?

Answer 2

The measure of combining ability of an atom with other atoms
-charge of an ion=valency

Question 3

Structure of a metal bond

Answer 3

Lattice of metal ions embedded in a sea of delocalised electrons
-electrons are mobile

*practice drawing a picture with headings

Question 4

Properties of a metal

Answer 4

-range of melting/boiling points
-good electric/heat conductors
-malleable
-lustre
-ductile
-high tensile strength
-hard

Question 5

Explain why metals have high melting/boiling points

Answer 5

-attraction between metal ions and electrons must be overcome in order for metal to melt/boil
-attractive forces are strong due to opposing charges
-thus, higher melting/boiling point is required

Question 6

Explain why metals are good conductors (heat and electricity)

Answer 6

Heat
-electrons move faster
-motion and energy transmitted through the lattice
-causing more vibration between particles and more collision

Electricity
-current in metal is electron flow
-as electrons repel, ones that are fed in a wire or rod of some sort will cause repulsion of electrons in the metal lattice
-and equal number of electrons will then be forced out of the wire onto the other end

Question 7

Explain why a metal is malleable, tensile, and ductile

Answer 7

Malleable:
-can be shaped or beaten
Ductile:
-drawn into wire
Tensile strength:
-pulled until snapping

For both:
-cations in lattice are arranged in layers with no real bonds
-only attraction to the electrons
-layers can slip over each other but will stay intact
-thus, metals can be deformed without breaking

Question 8

Explain why a metal has lustre

Answer 8

Light rays hitting the metal are reflected off of delocalised electrons
-close packing of metal ions prevent light from passing through
- e.g. opaque

Question 9

Structure of ionic bond

Answer 9

Electrostatic attraction between positively and negatively charged ions arranged in a crystalline arrangement

Question 10

Properties of ionic bonds

Answer 10

-strength (hard and brittle)
-good conduction of electricity (when dissolved)
-high melting point

Question 11

What is an alloy?

Answer 11

A substance formed when other material are mixed with a metal.
E.g. Materials like carbon

Question 12

Explain strength of ionic bond

Answer 12

Hard and brittle:
Can snap
-brittle because they can shatter easily when dropped
-attraction is strong but can be repulsed when layers shift
-no delocalised electrons

Question 13

Explain the conductivity of ionic bonds

Answer 13

Is very good when the ionic compound is melted or dissolved
-can’t conduct when solid due to ions being in fixed layers (no free electrons)
-when melted, ions and electrons are free to move thus conduct (electrolysis)

Question 14

Explain the melting/boiling point of ionic bonds

Answer 14

Solid at room temperature
-many non directional bonds held together by attraction of opposing charges
-with higher attraction=higher melting point
-no such thing as a single ionic bond i.e. no lattice

Question 15

Structure of a covalent bond

Answer 15

Non-metals bond and share an electron to attain a full shell
-directional bonding

*practice drawing the diagram with headings

Question 16

What is meant by covalent molecular?

Answer 16

Consists of a pair of electrons between two positive nuclei.
-the nuclei repel each other but are attracted by the pair of electrons

Question 17

What is a covalent network?

Answer 17

Bonds between substances are covalent (share electrons) but th eparticles of which they are built are atoms so they can be giant atomic structures
-all atoms are linked and strong bonds
-continuous bonds (network)
-no separate molecules
e.g. diamond, graphite, silica

Question 18

Properties of covalent bonds (molecular and network)

Answer 18

Molecular:
-low boiling point (weak intermolecular bonds)
-strong intramolecular bonds
-non-conductors (no free electrons)
-usually liquid/very soft

Network:
-high boiling/melting point
-non-conductors

Question 19

What is an allotrope?

Answer 19

different forms of the same element

Question 20

What are the allotropes of carbon?

Answer 20

Diamond, Graphite, Fullerenes

Question 21

Properties of diamond

Answer 21

Carbon atoms bound to 4 neighbouring atoms (4 valence electrons)
-forms a 3D covalent network
-no weak intermolecular forces therefore:
-really hard
-high boiling point
-non-conductor
-unreactive
-non-malleable or ductile

Question 22

Properties of graphite

Answer 22

High melting point.
Density lower than that of diamond.
It has soft, slippery feel

Question 23

How do ions related to the properties of bonds?

Answer 23

-when atoms with similar ionic charges are bonded together, their electrostatic attraction is higher
-so things like melting point are higher