IB Chemistry Topic 1-5 Vocabulary

Relative atomic mass
Average or (weighted) mean of masses of all isotopes of an element; relative to (one atom of) C-12
Relative molecular mass
The sum of the relative atomic masses of the constituent atoms of a molecule
Empirical formula
A formula showing the lowest whole number ratio of atoms in a compound
Molecular formula
A chemical formula of a molecular compound that shows the types and numbers of atoms present in a molecule of a compound (but not the structure)
Substance that is dissolved
A liquid substance capable of dissolving other substances
A homogeneous mixture of two or more substances
Mass number
The sum of the number of neutrons and protons in an atomic nucleus
Atomic number
The number of protons in the nucleus of an atom
Continuous spectrum
A spectrum of light in which there are no gaps, so that each region blends directly into the next
Line spectrum
A spectrum showing only certain discrete wavelengths/lines. on a black background
A vertical column of the periodic table
A horizontal row of the periodic table
Ionization energy
The amount of energy required to remove one mole of electrons from one mole of atoms in the gaseous state
The (minimum) energy required/needed for the removal of one electron; from a gaseous atom
Exothermic reaction
A reaction that releases heat energy to the surroundings ?H=-
Endothermic reaction
A reaction that absorbs heat energy from the surroundings ?H=+
Standard enthalpy change of reaction
The difference between the enthalpy of the products and the enthalpy of the reactants under standard conditions represented ?H
Bond enthalpy
The energy change required to break 1 mol of bonds or form 1 mol of bonds between two covalently bonded atoms in the gaseous state
Average bond enthalpy
Energy for the conversion of a gaseous molecule into (gaseous) atoms; (average values) obtained from a number of similar bonds/compounds
Atom of same element/same number of protons but with different mass number/number of neutrons