Higher Chemistry Definitions

Practically All Higher Chemistry Definitions you would need to know

Lattice

A regular repeating structure

Malleable

The ability to be rolled into sheets

Ductile

The ability to be stretched

Physical properties

 Properties which do not involve the substance in chemical reactions

LDF

The electrostatic attraction between a temporary and

Instantaneous dipole and induce dipole

Covalent Bond

The electrostatic attraction between a shared pair of electrons and

The positively charged nuclei  of the two atoms which are sharing these electrons.

First Ionisation Energy

The first ionisation energy of an element is the energy required to remove one electron from every atom in a mole of free atoms

Second Ionisation Energy

The second ionisation energy is the energy required to remove a second electron from every atom in a mote of free atoms once a first electron has already been removed

Electronegativity

Electronegativity is a measure of the attraction an atom which is involved in a covalent bond  has for the shared electrons of the bond

Period/Row

H

orizontal line of elements on the periodic table

Column/Group

Vertical column of elements in the periodic table having same # of outer electron and similar chemical properties

Covalent Bond

The electrostatic attraction between positive nuclei and negatively charged pair of electrons shared between them

Ionic

The electrostatic attraction between a positive and negative ion

Van der Waals’ forces.

Any intermolecular forces acting to attract one molecule to another molecule

Polar Molecule

Is a molecule which has a permanent slightly positive charge on one side and a permanent slightly negative charge on the other. Polar molecules have permanent dipoles

Hydrogen Bond

Is an unusually strong permanent dipole-permanent dipole interactions which will be found between any molecules containing O-H, N-H or F-H covalent bonds.

Permanent dipole-permanent dipole interactions

Are intermolecular forces of attraction between polar molecules.

Viscosity

Is another term for thickness of a liquid

Miscible

Liquids which dissolve in each other

Immiscible

Liquids which do not dissolve in each other and form two separate layers

Oxidation

Is a process in which electrons are lost

(OIL RIG)

Reduction

Is a process in which electrons are gained

(OIL RIG)

Redox Reaction

Are ions which appear unchanged on both sides of an equation, they do not take part in a reaction.

Oxidising Agent

Is a chemical which acts on another substance to oxidise it.

Reducing Agent

Is a chemical which acts on another substance to reduce it.

Displacement Reaction

Is a redox reaction in which one element is replaced by another in a compound.

Concordant

Results are titres that are very close together.

(Within about 0.2 cm³)

Redox Titration

The concentration of an oxidising or reducing agent is determined by measured how much is required to react completely with another substance.

Functional Group

is that part of a molecule which gives the substance its characteristic properties

Homologous Series

Is a family of compounds with the same general formula and similar chemical properties.

Isomer

Are compounds with the same molecular formula but different structural formulae

Distilation

Is a method of separating miscible liquids which have different boiling points by evaporation followed by condensation.

Distillate

The liquid which has been separated from the mixture as a result of distillation

Condensation Reaction

Occurs when two molecules are joined together with the loss of a small molecule- usually water.

Hydrolysis

Is a reaction in which a molecule is split up by the chemical action of water.

Reversible Reaction

Is a reaction that can go in both the forward direction and in the reverse direction.

Enzymes

Are proteins which acts a biological catalyst

Essential Amino Acids

Are amino acids that cannot be synthesised by the human body and must be present in the diet.

Volatile Molecule

One that easily evaporates

Denaturing

Is the word used to describe the change that happens when the intermolecular bonds holding a protein chain into a certain shape are broken.

Aldehyde

Is a molecule containing a primary carbonyl group. (The carbonyl group is connected to no more than one carbon atom).

 

Ketone

Is a molecule containing a secondary carbonyl group. (The carbonyl group is connected to two carbon atoms).

Rancid

word used to describe the foul smelling products produced when edible oils react with oxygen from the air.

Antioxidants

 Are molecules that reduce the rate of oxidation reactions by donating  electron(s) to an oxidising agent. They are, themselves, reducing agents.

Saponification

Is the process of making soap by hydrolysing edible oil using an alkaline solution

A Detergent

Is a cleaning product having molecules that have both hydrophilic (polar) and hydrophobic (non-polar)parts.

Hard Water

Is water containing relatively high concentrations of Ca²⁺(aq) or Mg²⁺(aq) ions.

Soft Water

Is water with very low concentrations of Ca²⁺(aq) or Mg²⁺(aq) ions.

Scum

Is an insoluble precipitate formed when Ca²⁺ or Mg²⁺ ions react with soap.

Soap less Detergents

Are substances that do not form scum in hard water. An example of a soap less detergent is shown

Emulsion

Contains small droplets of one liquid dispersed in another liquid.

Essential Oils

Are concentrated extracts of the volatile, non-water soluble aroma compounds from plants.

Free Radicals

Are atoms or fragments of a molecule with unpaired electrons and, as a result, are highly reactive.

Initiation Reaction

Is one in which two free radicals are formed by breaking the bond in a molecule. This step requires an input of energy- (UV light or sometimes heat)

Propagation Reaction

Is one in which a free radical reacts with a molecule to form a new free radical. A new molecule is formed too in this step.

Termination Reaction

Is one in which two radicals meet and form a stable molecule. The unpaired electrons from each radical come together to form a covalent bond.

Free-radical Scavenger

Is a molecule which can react with free radicals to form a stable molecule, stopping a chain reaction.

Gram Formula Mass (GFM)

The mass in grams of 1 mole of a substance

Limiting Reactant

Is the one which is completely used up in a chemical reaction (This will be the most expensive chemical in the reaction)

Excess Reactants

Are ones that are not used up completely in a chemical reaction (These will be the cheaper chemicals in the reaction)

Percentage Yield

Is a measure of the efficiency with which the reactants have been converted into the final product.

Atom Economy

Measures the potential amount of waste through the production of by-products for any reaction.

(An atom economy of 100% indicates that no by-products are produced) 

Molar Volume

Is the volume (measured in litres) 1 mole of that gas occupies at a certain temperature and pressure.

Activated Complex

Is the unstable arrangement of atoms formed- at the maximum of the potential energy barrier.

Activation Energy

Is the additional potential energy which has to be achieved by colliding molecules to form an activated complex.

Enthalpy

Is a measure of the chemical energy stored, within substances.

Exothermic Reaction

Reaction is a chemical change that gives out heat energy.

Endothermic Reaction

 Reaction is a chemical change that takes in heat energy.

Enthalpy Change

For a reaction is difference between the final total enthalpy of the products and the original total enthalpy of the reactants. The symbol for enthalpy change is ∆ H and the units are kilojoules (kJ). 

Enthalpy of Combustion

Is the enthalpy change when 1 mole of a substance burns completely in oxygen, all reactants and products being in their standard states at 25 ⁰C and one atmosphere

Hess’s Law

States that the overall enthalpy change in a reaction, or sequence of reactions, depends only on the reactants and products and not on the route taken.

Bond Enthalpy

Is the energy required to break one mole of bonds and form two separate atoms, all species being in the gaseous state. 

Mean Bond Enthalpy

Is the average energy required to break one mole of bonds, which can occur in a variety of environments, to form two separate atoms, all species being in the gaseous state. 

Hydroxyl Group

Alcohols

Functional group is -OH

General Formula is C_nH_2n+₁OH

Carbonyl Group

Carboxyl Group

Ester Link

Gives a fruity smell

Functional Group is -COO

General Formula

Aldehyde