ions + bonding

What charge will group 1 ions have?

+1

What charge will group 2 ions have?

+2

What charge will group 7 ions have?

-1

What are the 3 types of chemical bond?

• ionic

• covalent

• metallic

What is an ionic bond?

electrostatic attraction between a positive ion and a negative ion

Why do atoms form ions?

so that they gain a full outer shell of electrons which makes them more stable

Describe how an ionic bond forms between a metal and a non-metal (3)

• metal transfers 1 or more electrons to the non-metal so they both have full outer shells

• this makes the metal a positive ion and the non-metal a negative ion

• the two oppositely charged ions will be held together by electrostatic forces of attraction

Structure of an ionic compound (3)

• giant ionic lattice

• closely packed and regularly arranged

• held together by strong electrostatic forces of attraction

Why are ball and stick diagrams not accurate?

• atoms are not perfect spheres

• they dont show the electrons

• atoms are relatively far apart, should be closer

3 Properties of ionic compounds

• high mp and bp

• conduct electricity when molten or aqueous but not solid

• brittle

Why do ionic compounds have high mp and bp?

strong electrostatic forces of attraction between the oppositely charged ions, so require a lot of energy to overcome

Difference between empirical and molecular formula

e: smallest whole number ratio of atoms in the elements within a compound

m: exact number of atoms of atoms in the elements within a compound

Describe a covalent bond

• 2 non-metals

• 2 atoms share a pair of electrons to gain a full outer shell

What is a ‘double bond’?

2 covalent bonds between the same atoms, meaning 4 electrons are being shared

3 ways of drawing covalent bonds

• dot and cross diagrams

• displayed formula

• 3d models

What 3 types of substances can covalent bonds form? And explain what each one is

• polymers - large molecule made of monomers

• giant covalent - all atoms bonded to each other in strong covalent bonds

• simple molecular - consists of small molecules

What is stronger, covalent bonds or intermolecular forces?

covalent

3 examples of giant covalent structures

• diamond

• graphite

• silicon dioxide

Describe the bonding in simple molecular structures

strong covalent bonds between the atoms of each molecule, but weak forces between the molecules

Why do simple molecular substances have low m.p and b.p?

weak intermolecular forces which require little energy to overcome