Term | Definition |
Cathode Rays | streams of negatively charged particles called electrons |
Daltons Atomic Theory | All matter is made up of very small particles called atoms,
All atoms are indivisable- they cannot be broken down into simper particles |
An Energy Level | is defined as the fixed energy value that an electron in an atom may have |
E=Hf | E is the definite amount of energy emitted from an atom
Hf; Light of defenite frequency or wavelength in emmision spectrum. |
An Orbital | a region in space within which there is a high probability of finding an electron |
An element | is a substance that cannot be split up into simpler substances by chemical means |
A triad | is a group of 3 elements with similar chemical properties in which the atomic weight of the middle one is approximately equal to the average of the other two |
Newlands Octaves | are groups of elements arranged in order of increasing atomic weight where the first and the eighth element of each group have similar properties |
Mendeleevs periodic law | When elements are arranged in oreder of increasing atomic weight (relative atomic mass), the properties of the elements vary periodically. |
The atomic Number | of an atom is the number of protons in the nucleus of that atom |
The Modern Periodic Table | Is an arrangement of elements in order of increasing atomic number |
What happens when elements are aranged in order of increasing atomic number? | The properties of the elements vary periodically |
The Mass Number | of an element is the sum of the number of protons and neutrons in the nucleus |
Isotopes | are atoms of the same element (they have the same atomic number) that have different mass numbers due to the different number of neutrons in the nucleus. |
Relative Atomic Mass | The average of the mass numbers of the isotopes of an element
As they occur naturally
Taking their abundances into account
Expressed on a scale in which the atoms of the carbon 12 isotope have a mass of exactly 12 units |
Hunds Rule of Maximum Multiplicity | States that when two or more orbitals of equal energy are available, them electrons occupy them singly before occupying them in pairs |
The Aufbau Principle | states that when building up the electronic configuration of an atom in its ground state, the electrons occupy the lowest available energy level. |
The Pauli Exclusion Principle | states that no more than 2 electrons may occupy an orbital and they have to have opposite spin. |
6X10[23] | the amount of particles that one mole of a substance may contain |
Mass of one mole of an element= | relative atomic mass in grams |
a) The relative molecular mass of a compound | is the sum of the relative atomic masses of all the atoms in a molecule of that compound. |
b)The relative molecular mass of a compound | the mass of one molecule of that compound compared with 1/12 of the mass of the carbon 12 isotope |
Mass of one mole of a compound = | relative molecular mass in grams |
Mass(in grams) | Relative molecular mass X number of moles |
2 H2 + O2 = | 2 H2O |
Molecular Formula | empirical formula X n (n is a whole number) |
Arhenius' definition of an acid | An acid is a substance that dissociates in water to produce H+ ions |
Arrheinius' definition of a base | A base is a substance that dissociates in water to produce OH- ions |
Bronsted Lowry Definition of a base | A base is a proton accepter |
Bronsted Lowrey fefinition of an acid | An acid is a proton donator |
Conjugate Base | An acid changes into a conjugate base when it donates a proton |
Conjugate Acid | A base turns into a conjugate acid when it accepts a proton |
Conjugate Acid Base Pair | any pair consisting of an acid and a base which differ by one proton |
Neutralisation | is a reaction between an acid and a base to form a salt and water |
The concentration of a solution | The amount of solute that s dissolved in agiven volume of slution |
1 Moler Solution | it contains one mole of solute dissolved i one litre of solution |
a Titration | a laboratory procedure where a measured volume of one solution is added to a known volume of another solution until the reaction is complete |
Oxidation | When an element loses electrons |
Reduction | when an element gains electrons |