1.37-1.53 Structure and bonding

What are the electron arrangements of noble gases?

full outer shells

Describe the main properties of noble gases:

Monatomic, inert, colourless, gas

Monatomic meaning

One atom

Inert meaning

Motionless/unreactive

Can electrons be bonded to noble gas atoms?

No, as they have full outer shells they can only lose atoms

How will non-metal atoms always combine?

They always combine to get full outer shells

Where does covalent bonding occur?

Between two non-metals

How are electrons arranged in covalent bonding?

Pairs of electrons are shared

What are lone pairs?

Pairs of outer electrons on an atom that aren't involved in covalent bonding

Covalent bond definition

The electrostatic attraction between a shared pair of electrons and two nuclei

What are simple molecular structures?

Molecules with intermolecular forces of attraction

What properties do simple molecular structures have?

Low melting and boiling points

Why do simple molecular structures have low melting points?

Only weak intermolecular forces need to be overcome, requires little energy, NO COVALENT BONDS BROKEN

What is Group 7 called?

The Halogens

Why do melting and boiling points increase as we go down the group of the Halogens?

Intermolecular forces get stronger as the molecular mass increases (intermolecular forces are determined by the number of electrons in the molecule)

What are the two giant covalent structures (allotropes of carbon)?

Diamond and graphite;

Number of covalent bonds each carbon atom forms in Graphite

3

Number of covalent bonds each carbon atom forms in Diamond

4

What is Graphite and Diamond's melting point and why?

Very high because of many strong covalent bonds have to be broken

How hard is Graphite and why?

Graphite is soft and slippery → layers of atoms can slide over each other due to weak forces between layers

How hard is Diamond and why?

Diamond is very hard as the atoms are bonded together in a rigid network

What is Graphite's electrical and thermal conductivity and why?

Graphite conducts electricity and heat because there are delocalised electrons

What is Diamond's electrical and thermal conductivity and why?

Diamond doesn't conduct electricity as there are no delocalised electrons. However, Diamond conducts heat very well as each carbon is bonded to 4 other carbons

What is another allotrope of carbon which has a simple molecular structure?

C60 fullerene;

Why does C60 fullerene have lower melting points than diamond and graphite?

It has a simple molecular structure so only weaker intermolecular forces need to be broken

Why is C60 fullerene not as hard as diamond?

Not a rigid or full a structure

Why does C60 fullerene not conduct electricity?

C60 fullerene has no delocalised electrons

Where does ionic bonding occur?

Between non-metals and metals

Ion definition

An ion is a charged atom

Ionic bond definition

The electrostatic attraction between a positive ion and a negative ion (a cation and an anion)

Why do metals form positive ions?

Metals are mostly in groups 1, 2, 3 of the periodic table so they have less electrons in their outermost shell -> easier to lose electrons, positive ion formed;

What is a positive ion called?

A cation

What is a negative ion called?

An anion

What structures do ionic compounds have?

Giant lattices (of positive and negative ions packed and weaved together in a regular pattern)

Why do ionic compounds have high melting points?

Giant structure with many strong ionic bonds → need to be broken → requires a lot of heat energy

How can ionic compounds conduct electricity?

ONly if the ions can move -> must be dissolved and melted to conduct as in a solid the ions are in fixed positions so can't move -> molten as a liquid ions can move;

How do you write ionic formulae?

Drop and cross

Al3+O2- = Al2O3;

What are non-metal charges for ions?

Group number - 8

What is the formula of a silver ion?

Ag+

What is the formula of a lead ion?

Pb2+

What is the formula of a copper ion?

Cu2+

What is the formula of a zinc ion?

Zn2+

What is the formula of an ammonium ion?

(NH4)+

What is the formula of a hydroxide ion?

OH-

What is the formula of a nitrate ion?

(NO3)-

What is the formula of a sulfate ion?

(SO4) 2-

What is the formula of a carbonate ion?

(CO3) 2-

Where is metallic bonding found?

Between metals (when they are elements on their own, NOT bonded in compounds)

List some physical properties of metals

High melting points, conduct electricity, malleable;

Are metals simple or giant structures? explain.

Giant structures as they have high melting points → many bonds need to be broken

What can a metallic structure be described as?

An array of positive ions surrounded by a sea of delocalised electrons

Metallic bond definition

Electrostatic attraction between positive ions and delocalised electrons

Why do metals have high melting points?

Giant structures → need to break strong metallic bonds → requires a lot of energy

Why can metals conduct electricity?

Delocalised electrons can move freely through the structure and carry charge

Why are metals malleable?

The layers of ions slide over each other quite easily