Bonding and Structure

Give the charge of ammonium (NH4)

+

Give the charge of hydroxide (OH)

-

Give the charge of nitrate (NO3)

-

Give the displayed formula for oxygen

O = O (Two lines represent a double bond) Oxygen - O2

What are cations?

Positively charged ions

Give the chemical formula for rubidium sulfate

Rb2SO4

What is metallic bonding?

Strong electrostatic attraction between cations (positive ions) and delocalised electrons/metal ions in a lattice structure with free flowing electrons

What are alloys?

Substances made from two or more different metals mixed together

How do non-metal atoms form ions?

They gain electrons to form negative ions

How do intermolecular forces change with the size of molecules?

They increase - increases the melting and boiling point as well as more energy is needed to overcome these forces

How do metal atoms form ions?

They lose electrons to form positive ions

Why do atoms form bonds?

To obtain a complete outer shell of electrons and thus to become more stable

Why are ionic compounds brittle?

When lattice is hit, layer of ions is shifted - ions with the same charge are lined up - like charges repel and so split the ionic lattice, causing it to shatter

non polar covalent bond

a covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge

Give five examples of negative ions

● Cl- ● Br- ● O2- ● S2- ● I-

What are the allotropes of carbon?

● Diamond ● Graphite

Describe the structure and properties of simple molecular covalent substances

● Do not conduct electricity - no ions or free electrons to carry a charge ● Small molecules ● Low melting and boiling points - forces of attraction between the molecules (intermolecular forces) are very weak - not a lot of energy is needed to overcome them exists as liquids/gases at rm temp

Describe and explain the properties of diamond

● Each carbon atom is covalently bonded to four other carbon atoms - creates a symmetrical giant lattice ● Strong and hard - the structure is tightly held together by strong bonds. ● High melting and boiling point - diamond contains large numbers of strong covalent bonds which required a lot of energy to overcome ● Does not conduct electricity - no free electrons or ions

State properties of ionic substances

● High melting and boiling point - strong electrostatic forces between oppositely charged ions - a lot of energy is needed to overcome these forces ● Do not conduct electricity when solid - ions in fixed positions ● Conduct when molten or dissolved in water - ions are free to move and carry a charge

Give the displayed formula for water

O / \ H H Water - H2O

Give the charge of carbonate (CO3)

2-

Give the charge of sulfate (SO4)

2-

polar covalent bond

A covalent bond in which electrons are not shared equally

What is a covalent bond?

A covalent bond is a shared pair of electrons between two non-metal atoms

Give the chemical formula for aluminium carbonate

Al2(CO3)3

Give the chemical formula for aluminium oxide

Al2O3

Give the chemical formula for calcium hydroxide

Ca(OH)2

Give the chemical formula for calcium bromide

CaBr2

Give the displayed formula for chlorine

Cl - Cl Chlorine - Cl2

Why are alloys harder than pure metals?

Different elements have different sized atoms. When elements are combined to form alloys, the different sizes make it harder for the layers to slide over each other, making them harder than pure metals (bronze,steel,brass)

What are allotropes?

Different structural forms of the same element in the same physical state

What are giant covalent structures?

Giant covalent structures have huge networks of covalently bonded atoms. Carbon often forms this type of structure because they can each form four strong covalent bonds.

Describe and explain the properties of graphite

Graphite is soft / slippery because there are only weak intermolecular forces between layers which allow the layers to slide over one another, it conducts electricity because there is one delocalised electron per carbon atom. The delocalised electrons are mobile charges. Each carbon atom forms three covalent bonds - creates sheets of carbon atoms arranged in hexagons There are no covalent bonds between the layers - only held together by weak intermolecular forces and so they are free to move - makes graphite slippery and soft High melting point - covalent bonds in the layers need a lot of energy to overcome

Give the displayed formula for methane

H | H - C - H | H Methane - CH4

Give the displayed formula for ammonia

H | H - N - H Ammonia - NH3

Give the displayed formula for hydrogen chloride

H - Cl Hydrogen Chloride - HCl

Give the displayed formula for hydrogen

H - H Hydrogen - H2

What is ionic bonding?

Ionic bonding is the electrostatic attraction between positive and negative ions. It is a relatively strong attraction.

What are ions?

Ions are charged particles. They are formed when atoms lose electrons (positive ions) or gain (negative ions) electrons. E.g. sodium positive ion, Na+ , has an electronic configuration of 2,8 (same as Ne). An atom of sodium has lost one electron.

Give the chemical formula for potassium oxide

K2O

Give the chemical formula for lithium nitrate

LiNO3

Give the chemical formula for magnesium nitrate

Mg(NO3)2

Give the chemical formula for magnesium oxide

MgO

Give the displayed formula for nitrogen

N ≡ N Nitrogen - N2

Give the chemical formula for ammonium chloride

NH4Cl

Give the chemical formula for sodium chloride

NaCl

What are anions?

Negatively charged ions

Describe the properties of metals

● High melting/boiling points - strong forces of attraction between the positive ions and the negative delocalised electrons - a lot of energy is needed to overcome these forces ● Good conductors of heat and electricity - delocalised electrons can carry a charge ● Malleable, shiny, strong soft - layers of ions can slide over each other whilst maintaining the attraction forces

What are the three types of bonding?

● Ionic ● Covalent ● Metallic

Give five examples of positive ions

● Na+ ● Mg2+ ● Al3+ ● Ca2+ ● Rb+

How are ionic compounds formed?

● Reaction of a metal with a non-metal ● Electron transfer occurs - metal gives away its outer shell electrons to non-metal

Describe the structure and properties of giant covalent structures

● Solids - atoms covalently bonded together in a giant lattice ● High melting and boiling points - strong covalent bonds between the atoms - a lot of energy is needed to overcome these forces ● Generally don't conduct electricity - no delocalised electrons (except graphite) arranged in regular repeating lattices

How are ionic compounds held together?

● They are held together in a giant lattice ● It's a regular structure that extends in all directions in a substance ● Electrostatic attraction between positive and negative ions holds the structure together.