Physical Chemistry Definitions Flashcards

1
Q

Atomic / Proton number

A

Number of protons in the nucleus of an atom.

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2
Q

Mass / Nucleon number

A

Sum of protons and nucleus in the nucleus of an atom.

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3
Q

Isotopes

A

Atoms of an element that have the same number of protons but different number of neutrons and hence different nucleon numbers.

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4
Q

S orbitals

A

Orbital that is spherically symmetrical about the nucleus. The larger the principal quantum number, the orbitals get larger and more diffused.

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5
Q

P orbitals

A

Three dumbbell shaped orbitals, mutually at right angles to each other. All three orbitals are degenerate, ie have the same energy.

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6
Q

d orbitals

A

d orbitals have different shapes

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7
Q

First Ionisation Energy

A

The energy needed to remove one mole of electrons from one mole of the gaseous atoms to form one mole of singly charged gaseous cations.

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8
Q

Relative isotopic mass of an isotope

A

The mass of one atom of the isotope to 1-12th the mass of one atom of C-12 isotope

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9
Q

Relative atomic mass of an element

A

The average mass of one atom of the element to 1-12th the mass of one atom of C-12 isotope

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10
Q

Relative molecular mass of a substance

A

The average mass of one molecule of the substance to 1-12th the mass of one atom of C-12 isotope

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11
Q

Relative formula mass of a substance

A

The average mass of one formula unit of the substance to 1-12th the mass of one atom of C-12 isotope

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12
Q

One mole

A

The amount of substance which contains the same number of particles as there are atoms in exactly 12g of C-12

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13
Q

Avogadro’s law

A

Equal volumes of all gases under the same conditions of temperature and pressure contain the same number of atoms/molecules.

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14
Q

Empirical formula

A

The simplest formula that shows the relative number of atoms of each element present in a compound.

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15
Q

Molecular formula

A

The actual number of atoms present in one molecules of the compound

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16
Q

Metallic bonds

A

Strong electrostatic forces of attraction between the metal ions and the ‘sea’ of delocalised electrons in a giant metallic structure.

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17
Q

Ionic bonds

A

Strong electrostatic forces of attraction between cations and anions in the crystal lattice of an ionic solid

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18
Q

Covalent bond

A

Strong electrostatic forces of attraction between a shared pair of electrons and two positively charged nuclei

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19
Q

Lewis Acid

A

An atom with vacant low lying orbital to accept a lone pair of electron

20
Q

Lewis base

A

An atom with a lone pair of electrons, available for donation

21
Q

Assumptions of Kinetic Theory applied to an Ideal Gas

A

Volume of gas molecules is negligible compared to the volume of the container.

Forces of attraction between the gas molecules as well as between the gas molecules and the walls of the container are negligible.

All molecular collisions are perfectly elastic. There is no loss of kinetic energy during collision.

22
Q

Enthalpy Change of Reaction

A

The amount of heat absorbed or evolved when molar quantities of reactants as shown in the chemical equation react together.

23
Q

Enthalpy Change of Formation

A

The amount of heat absorbed or evolved when one mole of a substance is formed from its constituent elements.

24
Q

Enthalpy Change of Combustion

A

The amount of heat evolved when one mole of a substance in its standard state is completely burned in excess oxygen.

25
Q

Enthalpy Change of Neutralisation

A

The amount of heat evolved when one mole of water is formed from the neutralisation between an acid and a base.

26
Q

Enthalpy Change of Atomisation

A

The amount of heat absorbed when one mole of free gaseous atoms is formed from its element.

27
Q

Bond Energy

A

The average amount of heat absorbed to break one mole of that particular bond in a particular compound in the gaseous state

28
Q

Electron Affinity

A

The amount of heat evolved when 1 mole of electrons is added to one mole of gaseous atoms to form one mole of singly negatively charged ions

29
Q

Lattice energy

A

The amount of heat evolved when one mole of the solid ionic compound is formed from its constituent free gaseous ions

30
Q

Enthalpy change of Hydration

A

The amount of heat evolved when one mole of free gaseous ions is dissolved in a large amount of water forming a solution at infinite dilution

31
Q

Enthalpy change of Solution

A

The amount of heat absorbed or evolved when one mole of a solute is dissolved in an infinite volume of water

32
Q

Hess’ law

A

The enthalpy change of a chemical reaction is dependent only on the initial states of the reactants and the final state of the products and is independent of the reaction pathway taken.

33
Q

Entropy

A

The degree of disorder, of matter and ways to distribute energy in the system

34
Q

Rate equation

A

Relation of the rate of reaction to the concentration of reactants raised to the appropriate power

35
Q

Order of reaction

A

The power to which the concentration of the reactant is raised in the experimentally determined rate equation.

36
Q

Dynamic equilibrium

A

A state where the rate of forward reaction equals to the rate of backwards reaction for a reversible reaction such that there is no net change in the concentration of reactants and products

37
Q

Le Chatelier’s Principle

A

If a change occurs in one of the conditions under which a reversible reaction is in dynamic equilibrium, the position of equilibrium shifts so as to minimise the change.

38
Q

Saturated solution

A

A solution containing a maximum amount of solute in a given amount of solvent such that the ions are in equilibrium with the solid

39
Q

Solubility

A

Solubility of a substance is the maximum amount of solute that dissolves in 1dm^3 of water to form a saturated solution at a stated temperature

40
Q

Arrhenius Acid

A

A substance that releases H+ ions

41
Q

Arrhenius Base

A

A substance that releases OH- ions

42
Q

Bronsted Acid

A

Proton H+ donor

43
Q

Bronsted Base

A

Proton H+ acceptor

44
Q

Definition of pH

A

-log [H+]

45
Q

Buffer solution

A

A solution where pH remains almost constant when small amounts of acid or alkali are added to it

46
Q

Suitable indicator

A

An indicator that has a working pH range which lies within the range of rapid pH change for the titration

47
Q

Standard electrode potential

A

The potential difference between a standard hydrogen electrode and the half cell in which reacting species are at molar concentrations of 1 mol dm^-3, 298k and 1bar.