Ionic, covalent and metallic structures. * Flashcards
What is an ion?
an atom or group of atoms with an electrical charge
How are ions formed? (4 points)
Key words:
atoms, outer shell, electrons. unequal, charge, metal, non-metal
- atoms with incomplete outer shells either lose or gain electrons
- the atom then has an unequal number of protons and electrons
- this means it has an overall charge
- one atom must be metal, and one must be non-metal
What charge will an atom that loses electrons have?
if it loses electrons, it will have more protons than electrons, giving it a positive charge
What charge will an atom that gains electrons have?
if it gains electrons, it will have more electrons than protons, giving it a negative charge
What charge will an atom that gains electrons have?
if it gains electrons, it will have more electrons than protons, giving it a negative charge
What does the group number show about the atom?
the number of electrons in the outer shell
Do groups 1-3 lose or gain electrons?
lose
Do groups 5-7 lose or gain electrons?
gain
Do metal atoms lose or gain electrons?
What charge will they have?
metal atoms lose electrons
they have a positive charge
Do non-metal atoms lose or gain electrons?
What charge will they have?
non-metal atoms gain electrons
they have a negative charge
What is a compound ion?
an ion made up of a group of atoms
Name five compound ions and give their formulae
- hydroxide = OH -
- sulfate = SO4 2-
- nitrate = NO3 -
- carbonate = CO3 2-
ammonium = NH4 +
What must an ion drawing always have?
- square brackets around the outside
- a + or - outside the brackets
What is an ionic bond?
an ionic bond is the electrostatic force of attraction between oppositely charged electrostatic ions
Ionic compounds:
Fill the gaps:
the formation of an _____ ____ involves the transfer of _________ from the _____ to the ___-_____
the formation of an ionic bond involves the transfer of electrons from the metal to the non-metal
Ionic formulae:
Fill the gaps:
the ratio of _____ to ___-_____ ions is the amount of ________ ____ or ______
some ionic __________ contain __________ ions so ________ are used
the ratio of metal to non-metal ions is the amount of electrons lost or gained
e.g KCl has a 1:1 ratio as its K+ and Cl- so it balances out
e.g. K2O has a 2:1 ratio as its K+ and O2- so 2 K ions are needed to balance the charge
some ionic compounds contain compound ions so brackets are used
e.g. calcium nitrate = Ca(NO3)2 which shows you have 1 Ca2+ and 2 NO3 ions
What is oxidation?
oxidation is losing electrons
What is reduction?
reduction is gaining electrons
Give three properties of ionic compounds
- conducts electricity when molten - the ions are free to move and carry a charge
- high melting and boiling point - giant lattice structure which requires a lot of energy to break
- soluble in water - attracted to the water molecules which carry a small electrostatic charge
What kind of structure do ions have?
ions have a giant ionic lattice structure
the lattice is formed because the ions attract each other and form a regular pattern with oppositely charged ions next to each other
What is covalent bonding?
a shared pair of electrons between 2 atoms
Which type of element can form covalent bonds? (metal/non-metal)
non-metal
How does covalent bonding happen? (4 points)
Key words:
non-metal atoms, pair of electrons, molecule, covalently bonded element, covalently bonded compound
- when two non-metal atoms overlap they share a pair of electrons
- this forms a molecule
- if the atoms are all the same type then it forms a covalently bonded element
- if the atoms are different then it forms a covalently bonded compound
What does the number of electrons on the outer shell show?
how many covalent bonds an element will form
What are intermolecular forces?
the attractions between molecules
What is a simple molecular structure?
a substance made of millions of weakly attracted small molecules
What is a giant molecular structure?
a lattice structure that is held together by strong covalent bonds, with no intermolecular forces
Give two examples of a giant covalent structure
diamond and graphite
What is an allotrope?
different physical forms of the same element
What are diamond and graphite both made up of?
lattice carbon atoms going in all directions
Give two points about diamonds structure
- has a 3D structure
- each carbon atom has strong covalent bonds with other atoms
Give four points about graphites structure
- each carbon atom has made covalent bonds with three other atoms on the same layer
- has a layered structure - atoms in the same layer are bonded by strong covalent bonds
- each layer is a giant covalent structure
- the layers are held together by weak intermolecular forces
Does diamond insulate or conduct electricity?
diamond is an electrical insulator
Does graphite insulate or conduct electricity?
graphite conducts electricity
What kind of structure do metals have?
a giant crystalline structure
What is metallic bonding?
strong electrostatic attractions between positive metal ions and sea of delocalised electrons
