Topic 2 Flashcards
Metallic Bonding
Electrostatic force of attraction between the nuclei of a metal cation and delocalised electrons
Malleability
Can be pressed into different shapes
Ductile
Can be drawn into wires
Ionic Bonding
Strong electrostatic attraction between oppositely charged ions
What two factors make ionic bonding stronger?
- Smaller the ion
- Larger the charge on the ion
TREND BETWEEN IONIC RAIUDS AND ATOMIC RADIUS
The ionic radius of a positive ion is smaller than atomic radius of the element.
(Na+ is smaller than Na)
The ionic radius of a negative ion Is larger than atomic radius or the element
(F is smaller than F-)
Physical properties of ions:
- High melting point
- Brittleness
- Poor electrical conductor WHEN solid , but GOOD when molten
- Soluble in water (0ften)
Existence of ions:
Electrolysis of copper(II) chromate (VI):
-Blue copper cations would migrate to the cathode
- Yellow chromate anions would migrate to the anode
There would be a green copper (II) chromate (VI)solution
Covalent bonding
Strong electrostatic attraction between the nuclei of two atoms and their bonding pairs of electrons
How is a covalent bond formed ?
The overlap of two atomic orbitals each containing a single electron
Bond strength down a group
Decreases
Ie Cl > Br > I
Bond strength with increasing covalent bonds
Increases
Electronegativity
The ability of an atom to attract a bonding pair of electrons
Electronegativity …. Down a group because:
Decreases
- greater atomic radius
- electron shielding increases
- nuclear charge increases
Electronegativity …. Across a period because:
Increases
- Nuclear charge increases
- Increased no. Of protons
