1C - Bonding

When are ions formed?

When electrons are transferred from one atom to another

What do elements in the same group have?

Same number of outer electrons and therefore same charges of ion

What is the ionic formula of ammonium?

NH4+

What is the ionic formula of carbonate?

CO32-

What is the ionic formula of hydroxide?

OH-

What is the ionic formula of nitrate?

NO3-

What is the ionic formula of sulfate?

SO42-

What holds positive and negative ions together?

Electrostatic attraction

What is ionic bonding?

Oppositely charged ions are held together in a lattice

What is a giant ionic lattice?

A large regular structure of electrostatically attracted ions

What is the electrical conductivity of ionic compounds like?

Only conduct when molten or dissolved as ions need to be free to move and carry charge

What is the melting point of ionic compounds like?

High melting points

What is the solubility of ionic compounds like?

Tend to dissolve in water as water molecules are polar and pull ions away from the lattice causing it to dissolve

What is a molecule?

When two or more atoms bond together

What molecules are held together by?

Covalent bonds

What does a single covalent bond mean?

A pair of electrons is shared

What are simple covalent compounds?

Compounds made up of many individual molecules that are held together by strong covalent bonds but molecules within are held together by weaker forces called intermolecular forces

What are the properties of simple covalent compounds?

Low mp + bp, electrical insulators

What are giant covalent structures also called?

Macromolecular

What is the structure of graphite like?

Layers of graphite in sheets with three covalent bonds each. The fourth electron of each carbon is delocalised. Sheets held together by weak van der waals.

Properties of graphite?

• Weak bonds between sheets easily broken so sheets can slide

• Electric current cans flow as there are delocalised electrons

• Graphite has a low density

• Very high mp due to strong covalent bonds

• Insoluble in any solvent

What is the structure of diamond?

4 covalent bonds between each carbon

Properties of diamond?

• Very high melting point

• Extremely hard

• Good thermal conductor

• Can’t conduct electricity

• Won’t dissolve in any solvent

What happens in a dative covalent (coordinate bond)?

One of the atoms provides both of the shared electrons when one doesn’t have an by available electrons to share

What are lone pairs?

Unshared electrons

What is a charge cloud?

An area where you have a large chance of finding an electron

What is the electron pair repulsion?

Charge clouds repel each other so the shape of a molecule is determined by this

Do bonding pairs or lone pairs repel more?

Lone pairs

What is the name and angle for a central atom with two bonding pairs?

• Linear

• 180

What is the name and angle for a central atom with three bonding pairs?

• Trigonal planar

• 120

What is the name and angle for a central atom with four bonding pairs?

• Tetrahedral

• 109.5

What is the name and angle for a central atom with three bonding pairs and one lone pair?

• Trigonal pyramidal

• 107

What is the name and angle for a central atom with two bonding pairs and two lone pairs?

• Bent

• 104.5

What is the name and angle for a central atom with five bonding pairs?

• Trigonal bipyramidal

• 120 and 90

What is the name and angle for a central atom with four bonding pairs and one lone pair?

• Seesaw

• 102, 86.5

What is the name and angle for a central atom with three bonding pairs and two lone pairs?

• T-shaped

• 87.5

What is the name and angle for a central atom with six bonding pairs?

• octahedral

• 90

What is the name and angle for a central atom with five bonding pairs and one lone pair?

• Square pyramidal

• 90

What is the name and angle for a central atom with four bonding pairs and two lone pairs?

• Square planar

• 90

What is electronegativity?

The ability to attract the bonding electrons in a covalent bond

What is dipole?

Difference in electronegativity between two atoms

What happens if charge is distributed unevenly around a molecule?

A permanent dipole

What are molecules that have a permanent dipole called?

Polar molecules

What happens when polar bonds are arranged evenly?

Charge cancels out

What are intermolecular forces?

Forces between molecules

What are Van der Waals forces?

Weak attractions between molecules that cause a temporary dipole in the atom next to it which starts a domino effect

Why do larger molecules have stronger vdw?

Larger electron clouds or closer together in straight lines

What are permanent dipole-dipole forces?

Weak electrostatic forces of attraction between partially positive and partially charged on neighbouring molecules

What is hydrogen bonding?

The strongest imf between hydrogen and nitrogen, flourine or oxygen. This is because they are very electronegative and pull the electrons away from the hydrogen.

Why is ice less dense than water?

Molecules make hydrogen bonds and form a regular lattice structure

What is the electrical conductivity of simple molecular compounds?

Don’t conduct

What is the melting point of simple covalent?

Low because weak forces

What is the solubility of simple covalent like?

Dissolves depending on how polarised the molecules are

What is metallic bonding?

Metal ions in a sea of negative delocalised electrons that forms a lattice

What is the melting point of metallically bonded substances?

High due to strong electrostatic between the positive metal ions and the sea of delocalised electrons

What is teh ability to be shaped like in metallic bonding?

No bonds holding specific ions together so they are malleable and ductile

What is the conductivity of metallic bonding like?

Delocalised electrons can poss kinetic energy and they are good electrical conductors

What is the solubility of metallic bonding?

Insoluble except in liquid metal

What is a solid like?

Particles very close together, high density, vibrate around a fixed point

What is a liquid like?

Similar density to solid, particles move about freely and randomly

What is a gas like?

Density is low, very compressible, particles move freely

How does melting and boiling work in simple covalent substances?

Bonds do not break, only have to overcome weak IMF

How does melting and boiling in large covalent structures work?

Covalent bonds need to be broken