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?

When a substance consists of 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 -> lots of strong covalent bonds have to be broken;

What is Graphite's hardness and why?

Graphite is soft and slippery → layers of atoms can slide over each other;

What is Diamond's hardness 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 -> bc there are delocalised electrons;

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

Diamond doesn't conduct heat and electricity as there are no delocalised electrons;

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

In giant covalent structures (diamond and graphite), strong bonds between electrons needs to be broken -> these bonds are stronger than intermolecular forces. In C60 fullerene 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?

It doesn't have any delocalised electrons so there isn't a spare electron to conduct electricity -> delocalised electrons can't go far/jump between C60 molecules;

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 eb 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, eg:

Al3+O2- = Al2O3;

What are non-metal charges for ions?

Group number - 8, always a negative charge;

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