bonding

What are cations?

positively charged ions

What are anions

negatively charged ions

What do ions in an ionic lattice attract?

Each ion attracts oppositely charged ions in all directions

How many ions are there in a giant ionic lattice?

Contains billions of ions. The actual number is determined by the size of the crystal

In a giant ionic lattice 1 ion of one charge is surrounded by how many ions of the opposite charge?

6

What is the definition of a giant ionic lattice?

A three dimensional structure of oppositely charged ions bonded together by strong ionic bonds

What is ionic bonding?

The electrostatic attraction between positive and negative ions

What state are ionic compounds at room temp and why?

-almost all solid at room temp
-insufficient Thermal energy to overcome strong electrostatic forces of attraction

What is the relative melting point of ionic compounds and why-?

-very high temperatures are needed to provide the large quantity of energy to overcome the strong electrostatic forces of attraction

When will ionic compounds have a higher melting point?

When they contain greater ionic charges as there is a stronger attraction between ions

What do ionic compounds dissolve in?

Polar solvents E.g water

What are the two main process of ionic compounds

-ionic lattice is broken down
-polar water molecules attract and surround each ion

Which ionic compounds won't be soluble

Those with large charges because the attraction may to strong for the water to break down

Can ionic compounds conduct electricity when solid and why?

-No
-ions are fixed in place within the ionic lattice and cannot move freely and carry electric charge

Can ionic compounds conduct electricity when molten or dissolved in water?

-yes
-ions are free to move due to a breakdown in the lattice through the break down of electrostatic charges between the ions
-positive and negative ions can move throughout the liquid and carry charge

What is the definition of covalent bonding

The overlap of atomic orbitals, each containing electrons, to give a shared pair of electrons. It works because the shared pair of electrons is attracted to the nuclei of both bonding atoms

What does 'localised attraction' mean in covalent bonding?

The attraction is solely between the shared pair of electrons and the nuclei of the bonded atoms

What does simple covalent bonding result in

A molecule

What are lone pairs?

Paired electrons that are not shared

How do multiple covalent bonds form

When two atoms share more than one pair of electrons

What is dative bonding

A covalent bond in which the shared pair of electrons has been supplied by one of the bonding atoms only. They were probably a lone pair of electrons in one of the bonded atoms

What is average bond enthalpy

Serves as a measurement of covalent bond strength. Larger = stronger bond

What is metallic bonding?

Strong electrostatic attraction between cations and delocalised electrons

What do the cations in a metallic structure do

They are fixed in place so they maintain structure and shape

What are delocalised electrons?

Electrons that are not associated with any single atom or any single covalent bond

What is a giant metallic structure?

Billions of metal atoms held together by metallic bonding
Regular 3d arrangement of cations held in place by delocalised electrons

Explain melting point in metals and why

-high melting point becuase of strong metallic finds between positive metal ions and delocalised electrons
-higher charge higher the melting point due to higher attraction and more delocalised electrons

Explain electrical conductivity in metals and why

Conduct electricity
-delocalised electrons which are mobile and free to move throughout the structure and carry charge
-more electrons higher conductivity

What is a giant covalent structure?

where all the atoms are bonded to each other by strong covalent bonds.

Explain boiling and melting pony in giant covalent structures

-high
-many strong covalent bonds must be broken
-requires a lot of energy in the form of heat

Can a giant covalent compound conduct electricity

-no if all the electrons are involved in bonding

• if they form less there is a delocalised electron which can carry charge

What are simple covalent bonding result

Substances made of small molecules held together by weak intermolecular forces

Why do simple covalent bonding have low melting and boiling pints

Only weak intermolecular forces need to be broken which are relitivey weak

Are simple covalent compounds soluble

-polar can dissolve in polar solvents
-non polar can dissolve in non polar solvents

Do simple covalent compounds conduct electricity

No they have no free ions or delocalised electrons

What is an allotrope

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

Give examples of allotropes of carbon

diamond and graphite and graphene

How does melting point vary across period 3 (Na- ar)

• Na-al increases as metallic bonding strengthens because of a higher charge
• Si: very high giant covalent structure
• gases low dimple molecules structures, larger molecules have stronger London forces