Chem 1 defininitions

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CHEM1 Foundation Chemistry
Definitions to Learn
1. Formulae & Equations
Atomic number number of protons in the nucleus of an atom
Mass number sum of the protons and neutrons in the nucleus of an atom
Isotopes atoms with the same number of protons but different
numbers of neutrons
Empirical formula simplest whole number ratio of the atoms of each element in
a compound
Molecular formula actual number of atoms of each element in a molecule
Atom economy mass of desired product x 100%
total mass of reactants
2. Mass Spectrometry & Electronic Structure
Relative atomic mass average mass of an atom relative to 1/12 of the mass of a
carbon12 atom
Relative molecular mass mass of a molecule relative to 1/12 of the mass of a
carbon12 atom
3. Moles
Mole unit for amount of substance
Avogadro constant, NA number of particles present in a mole (6.02 x 1023 mol1)
4. Bonding & Periodicity
Lattice a regular 3dimensional array
Ionic bond electrostatic attraction between oppositely charged ions in a
Covalent bond a shared pair of electrons
Dative covalent bond covalent bond formed by donation of a lone pair
Metallic bond a lattice of positive ions surrounded by delocalised
Electronegativity ability of an atom to attract the electrons in a covalent bond

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Polar bond electrons are shared unequally (due to difference in
electronegativity of atoms at either end)
1st ionisation energy energy change when one mole of electrons is removed from
one mole of gaseous atoms…read more

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Homologous series a series of organic compounds with:
the same general formula
difference of CH2 between each member
a trend in physical properties
similar chemical properties
Functional group a group of atoms responsible for the characteristic
reactions of a compound
Structural isomers same molecular formula, different structures
Hydrocarbon a compound that contains hydrogen and carbon only
Saturated contains only single CC bonds
Fractional distillation separates due to differences in boiling point
Fraction mixture of compounds of similar boiling point
Cracking breaking a long chain…read more

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CHEM1 Foundation Chemistry
1. Formulae & Equations
Molar mass* Sum of masses of elements in formula
e.g. 106.0 for Na2CO3 (always give to 1 dp)
Percentage by mass Mass of specified element x 100%
Molar mass
e.g. 43.4% for Na in Na2CO3
Empirical formula For each element, divide percentage by relative atomic mass
Divide through by smallest
If result is, say, 1 1 1.5, then double to get whole numbers.
Do not round 1.…read more

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K = C+273…read more


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