Unit 1 Flashcards
Oxidation Number
The number of electrons that need to be added to (or taken away from) an element to make it neutral
Atomic Number
The number of protons in the nucleus of an atom
Mass Number
Is the number of protons + the number of neutrons in the nucleus of an atom
Isotopes
Are atoms having the same number of protons but a different number of neutrons
Ion
Is a particle where the number of electrons does not equal the number of protons
Positive Ions (Cations)
Form when an atom loses one or more electrons
Eg: K —> K(+) + e-
Negative Ions (Anions)
Form when an atom gains one or more electron
Eg: F + e- —> F(-)
Alpha Particles
They are a cluster of two protons and two neutrons and are therefore positively charged
Beta Particles
Fast moving electrons and therefore are negatively charged
Gamma Rays
High energy electromagnetic radiation therefore no charge
Half-life
Time taken for half the atoms in a radioisotope to decay
Atomic Orbital
Is a region within an atom that can hold up to two electrons with opposite spins
Electronic Configuration
Arrangement of electrons in an atom
First Ionisation Energy
The energy required to remove one electron from each atom in one mole of its gaseous atoms
X (g) ——> X+ (g) + e-
Nuclear Energy
The greater the nuclear charge, the greater the attractive force on the outer electron
Electron Shielding
The repulsion between electrons in different shells. Inner shell electrons repel outer shell electrons.
Therefore the more filled inner shells or sub-shells there are, the smaller the attractive force on the outer electron
Distance of outer electron from the nucleus
The greater the distance, the smaller the attractive force on the outer electron
Successive Ionisation Energy
The measure of energy needed to remove each electron in turn until all the electrons are removed from an atom
Convergence Limit
When spectral lines become so close together they have a continuous band of radiation and separate lines cannot be distinguished
Relative Atomic Mass
Average mass of one atom of the element relative to one-twelfth the mass of one atom of Carbon-12
Relative Isotopic Mass
Mass of one atom of an isotope relative to one-twelfth the mass of one atom of Carbon-12
Relative Formula Mass
Of a compound is the sum of the relative atomic masses of all atoms present in it’s formula
Mass Spectrometer
Used to calculate the average mass of an atom of an element, the mass of the isotopes of the element together with their relative abundances known
Molecular Ion
Positive ion formed in a mass spectrometer from a whole molecule
Fragmentation
Splitting of molecules, in a mass spectrometer, into smaller parts
One Mole
Is the amount of any substance that contains the same number of particles as there are atoms in exactly 12g of Carbon-12
Avogadro’s Constant
The number of atoms per mole (6.022 X 10 power of 23 mol-1)
Molar Mass
The mass of one mole of a substance
Stoichiometry
Molar relationship between the amounts of reactants and product in a chemical reaction
Empirical Formula
The simplest formula showing the simplest whole number ratio of the number of atoms of each present element
Molecular Formula
Shows the actual number of atoms of each element present in the molecule. It is a simple multiple of the EF
Molar Volume
The volume per mole of a gas, Vm
Atom Economey
Mass of required product
———————————- X 100
Total mass of reactants
Percentage Yield
Mass of product obtained
———————————— X 100
Max theoretical mass of product
Ionic Bond
Is a bond formed by the electrical attraction between positive and negative ions
Covalent Bond
Has a pair of electrons with opposed spin shared between two atoms with each atom giving one electron
Coordinative Bond
Covalent bond in which both shared electrons come from one of the atoms
Electronegativity
Measure of the ability of an atom in a covalent bond to attract the electron bonding pair
Polar Bond
Has one end of the bond with a slightly positive charge and the other end with a slightly negative charge
I.E, a dipole (neutral)
Dipole
Separation of charge within a molecule
Intermolecular Bonding
Weak bonding holding the molecules together
Eg: a liquid and governs the physical properties of a substance
Intramolecular Forces
Strong bonding between the atoms in a molecule and governs its Chemistry
Van Der Waals Forces
Weak intermolecular forces made up of dipole-dipole and induced dipole-induced dipole forces of attraction
Hydrogen Bond
Relatively strong intermolecular bond having a hydrogen atom joined to a very electronegative element in a a molecule and bonding to another electronegative element in another molecule
Bond Pair
Two electrons having opposed spins that bond two atoms in a molecule together by a covalent or coordinate bond
Lone Pair
Two electrons having opposite spins that belong to one atom only and are not involved in bonding to other atoms
Solute
Substance that dissolves in the solvent (can be solid, liquid or gas)
Solvent
Liquid medium in which the solute dissolves, commonly water
Saturated
Solution that cannot dissolve any more solute under the existing conditions
Polar
Molecule with separation of delta positive and delta negative charge
Crystal Coordination Number
The number of anions around each cations in an ionic lattice and vice versa
Delocalised
Means that an electron is not attached to a particular atom - it can move around between other atoms
Reducing Agent
Gives the electron to another species that is therefore oxidised by its loss
Oxidising Agent
Remove an electron from another species and it is therefore reduced
Redox
A chemical reaction in which an electron is transferred from one species - the reducing agent - to another species, which is reduced by the receiving the electron
Volatility
Describes how readily a substance vaporises
Electronegative Element
Having a strong affinitive for an electron in this acting as an oxidising agent
Dynamic Equilibrium
When the forward and reverse reactions occur at the same rate
Revirsible Reaction
One that can go in either direction, depending on the condition
Position of Equilibrium
The proportion of product to reactants in an equilibrium mixture
Le Chatelier’s Principle
States that other system are equilibrium is subjected to a change. The equilibrium tends to shift as to minimise the effect of change.
Acid
Is a proton (H+) donor
Base
Is a proton (H+) accepter
A Strong Acid
Fully disassociates in aqueous solution
Eg: HCL
A Weak Acid
Partially disassociates an aqueous solution
Eg: CH3COOH
pH
-log10[H+]
A Salt
Compound that forms on a metal ion replaces the hydrogen ion in an acid
Standard Solution
The concentration is accurately known
