BONDING Flashcards
State how ions form and why they attract each other
- Ions form when atoms lose or gain electrons
- Since electrons are negatively charged, an atom that loses one or more electrons will become positively charged
- An atom that gains one or more electrons will become negatively charged
What’s ionic bonding
Bonding that involves electrostatic attraction between oppositely charged ions in a lattice
Formula of sulfate ion
SO₄²-
Formula of hydroxide ion
OH¯
Formula of nitrate ion
NO3-
Formula of carbonate ion
HCO3-
Formula of ammonium ion
NH₄⁺
State the properties of ionically bonded compounds
- High melting and boiling points > ions in giant ionic lattice are held by strong electrostatic forces of attraction acing in all directions> difficult to overcome
- Conduct electricity when molten or dissolved in solution > ions of the compound are able to move and carry charge. Unable to conduct when solid as ions are fixed in place so unable to carry charge
- Soluble in water > both ionic compounds and water molecules are partially charged molecules (polar). > means the partial charges of water break apart the ionic lattice, pulling oppositely charged ions apart and the ionic compound to dissolve.
-Always solids at room temperature > have giant structures and therefore high melting temperatures > in order to melt an ionic compound, a lot of energy is required to break up the lattice of ions
- Brittle and shatter easily when given a sharp blow > they form a lattice of alternating positive and negative ions
Describe the structure of ionically bonded compounds
The structure of this ionic compound is a giant lattice with oppositely charged ions and strong electrostatic forces (attractive forces between ions) between them
Describe a covalent bond
- Forms between 2 non-metals
- Atoms share some of their outer electrons so that each atom has a stable noble gas arrangement
Describe a co-ordinate bond (dative covalent)
- Bonds contains a shared pair of electrons with both electrons supplied by one atom
Describe the properties of covalently bonded molecules
- Substances composed of molecules are gases, liquids, or solids with low melting points > the strong covalent bonds are only between the atoms within the molecules > there’s only a weak attraction between the molecules so the molecules don’t need much energy to remove the bonds
- Poor electrical conductors > molecules are neutral overall > no charged particles to carry current
- When dissolved in water, they remain as molecules > solutions don’t conduct electricity > no charged particles
Define electronegativity
measure of tendency of an atom to attract a bonding pair of electrons in a covalent bond
-greater the e.n. of an atom the more it attracts electrons towards it
Factors that affect electronegativity of an atom
-atomic charge
-distance from nucleus (atomic nucleus)
-electron sheilding
Non-polar covalent bonds
no difference between electronegativities e.g. Cl-Cl
-symmetrical molecules are non-polar even though they contain polar bonds
Polar covalent bonds
Small difference between electronegativities e.g. H-Cl
Ionic bond
Large difference in electronegativities
Difference between intermolecular and intramolecular forces
Intermolecular - attractive forces between neighbouring molecules
intramolecular -bonds that act WITHIN one molecule
Linear shape
- Total number of electron pairs = not applicable
- 1 bonding pair of electrons
- lone pairs not applicable
- bond angle = 180
-e.g. H2 and HCL
Linear Shape (2)
- Total number of electron pairs = 2
- 2 bonding pair of electrons
- 0 lone pairs
-180
-e.g. C02 HCN
Trigonal Planar
- 3 electron pairs
- 3 bonding pairs
- 0 lone pairs
-120
e.g. Al, Cl3, Bcl3
V-shaped/ bend/ non linear
- 4 electron pairs
-2 bonding pairs - 2 lone pairs
-104.5
-e.g. H2O
Tetrahedral
-4 electron pairs
-4 bonding pairs
-0 lone pairs
-109.5
-e.g. CH4
Triangular pyramid
-4 electron pairs
-3 bonding pairs
-1 lone pair
-107
-e.g. NH3
