Term | Definition |
An Energy Level | 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 |
An Orbital | The region in space within which there is a high probability of finding an electron |
Arrhenius's Definition of an Acid | An acid is a substance that dissociates in water to produce H+ ions |
Arrhenius's Definition of a Base | A base is a substance that dissociates in water to produce OH- ions |
Bronsted Lowrey definition of a Base | A base is a proton acceptor |
Bronsted Lowrey definition of an Acid | An acid is a proton donator |
Acid changes to conjugate base | When an acid donates a proton |
Base changes to conjugate acid | When the base accepted the proton |
A Conjugate Acid-Base pair | Any pair consisting of an acid and a base which differ by one proton |
Neutralisation | The relationship between the acid and the base to form a salt and water |
Acid + Base | Salt & Water |
Concentration of a solution | The amount of solute dissolved in given volume of solution |
A 1 Molar solution | It contains one mole of the solute that is dissolved in onle litre of solution |
Number of Moles | Volume X Molarity divided by 1000 |
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 |
A Primary Standard | A substance which can be obtained in a stable, pure and soluble solid form so it can be weighed out and dissolved in water to give a solution of accurately known solution |
The atomic radius of an atom | Half the distance between the nuclei of 2 atoms of the same element that are joined together by a single covalent bond |
The Values of atomic radius increases down any one group in the periodic table | -New Shell
-Screening effect of inner electrons |
The values of Atomic Radius decrease from left to right across a period | -Increasing Nuclear Charge
-No increase in the screening effect |
Ionisation Energy | The energy needed to steal an electron |
The first Ionisation Energy | The energy required to completely remove the most loosely bound electron from a neural gaseous atom |
The values of ionisation energy decrease down the groups in the periodic table | -Increasing Atomic Radius
-Screening effect of inner electrons |
The values of ionisation energy increase across the periods | -Increasing nuclear charge
-Decreasing atomic radius |
The values of electronegativity decrease down a group in the periodic table for 2 reasons | -Decreasing atomic radius
-Increasing Nuclear charge |
A Gas | A substance that has no well defined boundaries and diffuses rapidly to fill any container in which it is placed. |
Temperature Celcius - Kelvin | Can be converted from Kelvin Scale by adding 273 |
1 KPa | 1000 Pa |
1 Litre | 1000cm3 / 1 Cubic Decimetre |
Boyles Law | At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure |
PV= | K |
Charles's Law | At constant pressure, the volume of a fixed mass of gas is directly proportional to its temperature. |
Avogadro's Law | Equal volumes of gases contain equal numbers of molecules, under the same conditions of temperature and pressure |
At S.T.P 1 mole of any gas occupies | A volume of 22.4L |
An ideal gas | Is one that obeys all the assumptions of the kinetic theory of gases under all conditions of temperature and pressure |
Real gases differ from ideal gases: | -Forces of attraction and repulsion between the molecules
-The volume of the molecules is not negligible |
A compound | A substance that is made of 2 or more different element combined together chemically. |
The octet rule | When bonding occurs, atoms tend to reach an electron arrangement with eight electrons in the outermost shell |
An Ion | A charged ion or group of atoms |
An ionic bond | the force of attraction between oppositely charged ions in a compound |
A transition metal | A metal that forms at least one ion with a partially filled d sub level |
A Molecule | A group of atoms joined together. It is the smallest particle of an element or compound that can exist independently |
The Valency of an element | The number of atoms of hydrogen or any other monovalent element with which each atom of the element combines |
Electronegativitey | The relative attraction that an atom in a molecule has for the shared pair of electrons in a covalent bond |
An electronegativity difference greater than 1.7 | indicates ionic bond |
Van der Waals Forces | Weak attractive forces between molecules resulting from the formation of temporary dipoles |
Dipole Dipole forces | The forces of attraction between the negative pole of a molecule and the positive pole of another molecule. |
Hydrogen Bonds | Particular type of dipole dipole attraction between molecules in which hydrogen atoms are bonded to Nitrogen, Oxygen and fluorine.The hydrogen atom carries a partially positive charge and is attracted to the electronegative atom in another molecule. |
One Mole of a substance | The amount of that substance which contains 6x10(23) particles of that substance |
Mass of one mole of a substance | Relative atomic mass in grams |
The relative molecular mass of a compound | The sum of the relative atomic masses of all the atoms in a molecule of that compound |
Mass of one molecule of a compound | Relative molecular mass in grams |
Molecular Formula = | Empiricle Formula X n (n is a whole number) |