Chemistry Test 3 Flashcards
List the properties of a metal
- High melting and boiling points
- Good conductors of electricity and heat
- Malleable; shaped by beating or rolling
- Ductile; drawn to wire
- High Density; hard with a high tensile strength
- Lustrous; shiny or reflective
- Reactive (corrosive)
- Have low ionisation energies (measure of the energy required to remove an electron of a gaseous atom)
- low electronegativity ( a measure of the tendency of an atom to attract a bonding pair of electrons
- react by losing electrons
Explain why metals have a high boiling and melting points
Strong electrostatic forces takes a lot of energy the to break apart the attractive forces in a metal
Why are metals good conductors of heat and electricity in solid and molten state.
The sea of charges and delocalised electrons which carry the electric current or heat energy to pass and cross through quickly lattice
Why are metals ductile and malleable?
The non-directional bonding in the metal means atoms can move out of the way when being manipulated
Why do metals have a high density?
The atoms are closely packed and clustered tightly together in the lattice structure
Why are metals lustrous?
The free electrons within the metal reflect light
Why are metals reactive?
The free electrons within the metal can be easily removed from the atom.
What are the main differences between the properties of the main group and transition group metals?
- Transition metals are harder
- Transition metals are more dense
- Transition metals have higher melting points
- transition metals have strong magnetic properties
- transition metal compounds tend to be brightly coloured
What is an ionic compound?
Ionic compounds are made by the combination of atoms or groups of atoms, where electron/s are transferred from one another.
They form a crystal lattice made up of positive and negative ions
What is ionic bonding?
Ionic bonding is a chemical bonding between a metal and a non metal, that involved the transfer of electrons from 2 or more atoms.
Why do ions form?
Ions are former when atoms lose or gain electrons in order to fulfil the octet rule and have full outer valence electron shells.
What type of force is responsible for holding the actions and anions together in an ionic lattice?
Electrostatic attraction / force exiting between the positively and negatively charged atoms
Explain the formula for Sodium chloride
In the case of sodium chloride, in order to maximise the forces of attraction, each sodium ion (Na+) is surrounded by six chloride ions (Cl-) and each chloride ions is surrounded by six sodium atoms.
1:1 ratio that is why it is written NaCL
List the properties of ionic compounds
- high melting and boiling points ( Solids at room temperature)
- Hard but brittle
- Do not conduct electricity in solid state
- good conductors of electricity in liquid or dissolved state
- vary from being soluble and insoluble in water
- not malleable or ductile
Explain why ionic compounds have melting points
Ionic bonds are very strong (due to electrostatic forces between the + and - ions), so a large amount of energy is required to break the bonds,
Strong electrostatic forces hold the + and - ions in fixed positions therefore High amount of energy is needed to disturb bonds.
Eg.
- Magnesium oxide is used to line furnaces
- Ceramic materials contain a mixture of strong ionic and covalent bonds which help be a part of engine parts
Explain why ionic compounds are hard but brittle
- Solid ionic compounds feel hard but can be easily broken when force is applied
- It feels hard because the electrostatic force hold the ions close together making it feel tough.
- When force is applied the ions are disturbed and moved from the fixed positions in the lattice (+-+-+-) to like charges (++++) causing repulsion, thus they break apart.
Eg.
- Calcium phosphate makes up Bone tissue (strengths bone but can break)
- Granite, limestone and Sandstone ( why they easily crumble but are heavy)
Why are ionic compounds good conductors of electricity in a liquid state?
In an aqueous solution (polar solvents such as water) the compounds dissolves and disassociates. This means there are free particles which are able to direct and move the current along.
However this cannot occur in a solid lattice because the particles are fixed in organised locations.
Eg.
- Ammonium Chloride is used as electrolyte in dry batteries which in solution allow current to flow in battery
- Potassium hydroxide is used as an electrolyte in ‘push’ remote buttons