Covelent and Ionic Bonds

What is an ionic bond

A bond between a metal and non-metal involving the transfer of e-

What happens to the e- when a metal and non-metal form an ionic bond

The metal atoms loses e- to become cations. The non-metals gain e- becomes anion

What is an ion

An ion is an atom or group of atoms with a positive or negative charge

If an ion is positively charged, has it lost or gained electrons?

It has lost electrons. There are fewer negatively charged electrons to cancel out the charge of the positive protons. This means the overall charge becomes positive.

What does it mean if an ionic compound ends in -ide?

The compound contains 2 elements.

What does it mean if an ionic compound ends in -ate

The compound contains at least three elements, one of which is oxygen

What is the structure of an ionic compound

- lattice structure

- regular arrangement of ions

- ions held together by strong electrostatic forces between ions with opposite charges

What is covalent bond

A bond formed when an electron pair is shared between two atoms

What forms as a result of covalent bonding

molecule

True of false? 'Covalent bonds are weak'

FALSE. Covalent bonds are the strong

Why do ionic compounds have a high m.p

Strong electrostatic attractions between the positive and negative ions requires a lot of energy to overcome

Do ionic compounds conduct and when?

Yes they do conduct, only when dissolved in a solvent, because the ions are charged and free to move

Why do simple molecular compounds have low m.p

They have weak intermolecular forces, less energy to overcome

Do simple molecular compounds conduct? Why or why not

No because there are no free e-

Do giant covalent conduct when molten

It's very poor except graphite

So which has a higher m.p and why. Simple molecular ( covalent) or giant

Simple Molecular

Low (weak forces)

Giant Covalent

Very High (strong bonds)

Describe the limitations of particular representations and

models to, include dot and cross, ball and stick models and

two- and three-dimensional representations-

Dot and Cross Models

Dot and Cross Models

• Show electron sharing/transfer but do not represent 3D structure.

Ball and Stick Models

○ Show 3D arrangements but may exaggerate distances between atoms.

2D and 3D Models

§ Simplified and may not show bonding angles accurately.

Do giant covalent structures have a high m.p? Why

Yes because they have lots of strong covalent bonds which requires energy

Do metallic bonds conduct electricity? Why

Yes they do, they conduct when molten since there is a sea of delocalised e-

Name two giant covalent structures formed from carbon atoms

graphite and diamond

Describe the structure of graphite

- each carbon atom bonded to 3 other carbon atoms

- layers of hexagonal rings of carbon atoms

- weak intermolecular forces between layers

- one delocalised e- per carbon atom

Describe and explain the properties of graphite

- graphite is a good lubricant. It's lubricating properties are as a result of absorbed gases on the surface of the carbon atoms. Graphites inability to act as an effective lubricant in a vacuum is the reason why it's not used as a lubricant in spacecraft

- it's a fairly good conductor of electricity. The delocalised electrons between the layers are free to move under the influence of an applied potential difference. It can only conduct parrallel to its layers though. The delocalised electrons are not free to move from one layer to the next

- graphite has a high melting temperature due to the great number of strong C-C bonds that need to be broken in order to melt it

Describe the structure of diamond

- all carbon atom are covalently bonded to four other carbon atoms

- no dealocolised e-

Properties of diamond

- very hard

- very high m.p

-doesn't conduct e- since no free e-

Properties of graphite

slippery, layered structure, bonds in layers are tight but between layers are weak

Properties of metal

- high m.p

- high density

-good conductor

- malleable

Why metal can conduct

The e- in the metals are charged and can move

Ionic bond is between what TYPE of atoms

Non metal and metal

Covalent bond is between what TYPE of atoms

Non metal and non metal

Dot cross diagram for ionic bond

Transfer of e- between atoms. So not actually joined. Its in the bracket

Dot cross diagram for covalent

Share e-. So there's an overlap between elements and they both complete its outer shell.

Recall that an ion is an atom or group of atoms with a positive

or negative charge

ions are an atoms that gained or lost e- resulting to charge. Cation ( positive charge and e- is lost) & Anion ( negative charge when e- are gained)

Explain the structure of an ionic compound as a lattice structure

consisting of a regular arrangement of ions held together by strong electrostatic forces (ionic bonds)

between oppositely

charged ions- giant lattice, alternating cations and anions. Held by strong electrostatic forces. High m.p due to strength of bond

Electrostatic forces

Ionic bonding

Weak intermolecular forces

Simple covalent bond ( so like molecules not graphite or any of that)