LC Chemistry - 5th Year Christmas Revision

Mole

Contains the Avogadro number (6 x 10^23) of particles or relative molecular mass in grams(g) or amount containing as many particles as the no. of atoms in 12g of carbon-12

Radioactivity

Spontaneous breaking up of a nucleus to release α, β or γ radiation

Alpha particle

Helium (He) nucleus or particle consisting of 2 protons + 2 neutrons

Radioisotope

Radioactive isotope or isotope (atom) with unstable nucleus

Half Life

Time taken for half of the nuclei in a sample to decay or Time taken for activity to reduce by(to) a half

Nuclear Reaction

Process that alters the composition, structure, or energy of a nucleus

(Radio) Carbon Dating

Dates an object containing carbon based on C-14 to C-12 ratio

Beta Particle

High speed electron emitted from the nucleus of a radioisotope following the conversion of a neutron into a proton + an electron

Relative Atomic Mass

Average mass of atoms of element compared (relative) to 1/12 mass of carbon-12 isotope

Isotopes

Atoms of same element with different mass numbers due to different number of neutrons or Atoms with same atomic number(Z) but different mass numbers (A)

Atomic energy levels

Fixed amount of energy of an electron in an atom

Atomic Radius

Half the distance between the nuclei of two identical atoms (of the same element)joined by a single covalent bond

Principle of Mass Spectrometry

Positively charged ions are separated by mass when moving in a magnetic field

Ground State

In lowest energy state or in n = 1 level (shell)

Excited State

Higher energy state or in n > 1 level (shell)

Atomic Number

Number of protons in nucleus of an atom

Mass Number

Number of protons + neutrons (nucleons) in the atoms of an isotope

Mendeleev's Periodic Law/System

When elements are listed according to relative atomic mass, their chemical properties repeat periodically

Modern Periodic Law/System

When elements are listed according to atomic number, their chemical properties repeat periodically

Triad

Group of 3 elements with similar chemical properties where the atomic weight of the middle one is approx.equal to the average of the other two

Rate of a Chemical Reaction

Change in concentration per unit time of any one reactant or product

Activation Energy

Minimum combined energy of particles for effective collisions or minimum combined energy of colliding particles for reaction to take place between them

Heterogeneous Catalysis

Catalyst in different phase (not state) from reactants (not products)

Catalyst

Substance that alters the rate of a reaction and is not used up (consumed) in reaction or Substance that provides alternative pathway for reaction that has a different activation energy

Effective Collision

One that results in a reaction (product formation) or reaches activation energy

Autocatalysis

A product of a reaction acts as a catalyst for the reaction

Catalytic Poison

Substance that makes catalyst inactive

Catalytic Converter

Device in exhaust which converts pollutants to less harmful substances

Enzyme

Biological catalyst

Homogeneous Catalysis

Catalyst in same phase (not state) as reactants (not products)