Chemical Structures And Equations Flashcards
Valency vs valence electrons
Valency refers to the number of electrons an atom can gain, lose, or share to form chemical bonds which will result in a complete outer energy level while valence electrons are the number of electrons present in the outermost energy level of an atom.
Valence electrons are the
Unpaired elections in an atom.
Electronegativity
Electronegativity is a measure of an atom’s ability to attract and hold onto shared electrons in a covalent bond, with higher values indicating a stronger attraction.
Covalent bonds
Sharing of electrons between 2 atoms. They form between two non metal atoms when the difference in electronegativity is less than 1,8.
Each atom contributes an electron to be shared by both atoms.
Covalent bonds are very strong bonds
Both nuclei attract the shared pair of electrons very strongly, it requires a lot of energy to break covalent bonds.
Covalent bonds always result in
The formation of molecules
Covalent bonds arise between
Two non metal atoms when their outermost energy levels overlap
Diatomic molecule
Made up of 2 atoms of the same kind of element
Simple ions
Carry a charge. They are also called monatomic ions.
Polyatomic ions
Groups of atoms bonded together which collectively carry a charge
H20
Hydrogen oxide
Water
Co2
Carbon dioxide
Carbon dioxide
NH3
Hydrogen nitride
Ammonia
HCl
Hydrogen chloride
Hydrochloric acid
H2SO4
Hydrogen sulphate
Sulphuric acid
HNO3
Hydrogen nitrate
Nitric acid
H2CO3
Hydrogen carbonate
Carbonic acid
H3PO4
Hydrogen phosphate
Phosphoric acid
CH3COOH
Ethanoic acid
Vinegar
NaCl
Sodium chloride
Table salt
NaOH
Sodium hydroxide
Caustic soda
CH4
Methane gas
Natural gas
CuSO4
Copper sulphate
Blue vitriol
MgSO4
Magnesium sulphate
Epsoms salt
CaSO4
Calcium sulphate
Gypsum
CaCO3
Calcium carbonate
Marble/chalk/limestone
KNO3
Potassium nitrate
Saltpetre
KOH
Potassium hydroxide
Caustic potash
NaNO3
Sodium nitrate
Chile saltpetre
Na2CO3
Sodium carbonate
Washing soda
NaHCO3
Sodium hydrogen carbonate
Bicarbonate of soda /baking soda
Chemical formula for Ionic substances
Write the symbol of the positive ion first then negative.
Write Ionic charges charges at the top right of symbols (1+:2+:3+:4+:3-:2-:1-.
Ionic bonds which arise from the
Transfer of electrons from one atom to the other.
Metallic bonds which arise from
Free valence electrons moving around a lattice of positive ions
Metallic bonds form between
Two metal atoms
Ionic bonds form between
A metal and non metal atom when the difference in electronegativity is greater than 1,7
Carbonate ion
CO3 TO THE power of 2-
Two types of covalent bonds
Polar and non polar/pure covalent bonds
Non polar bonds
When covalent bonds form between atoms of an element, and both atoms have the same value of electronegativity, both of the atoms have the same pull of electrons. The bonded electron paid us shared equally.
Polar covalent bonds
When 2 elements carrying different electronegativity value bond chemically results in electrons being pulled to the one with more electronegativity, electrons are being shared unequally
