Chemistry definitions

Question 1

Daltons atomic theory

Answer 1

All matter is made up of very small particles called atoms
All atoms are indivisible
They cannot be broken down into simpler particles

Question 2

Cathode rays

Answer 2

Streams of negatively charged particles called electrons travel in straight lines. They have sufficient energy to move a paddle wheel

Question 3

Element

Answer 3

The substance which cannot be divided into simpler substances by chemical means

Question 4

Atom

Answer 4

Is the smallest part of an element that can take part in a chemical reaction.
Atoms are indivisible they can not be broken down into simpler particles.

Question 5

Molecule

Answer 5

a group of atoms joined together.

It is the smallest particle of any element or compound that can exist independently.

Question 6

Compound

Answer 6

Is formed when two or more elements are combined chemically

Question 7

Mixture

Answer 7

Is formed when two or more substances are mixed together but do not combine chemically

Question 8

Atomic number

Answer 8

Is the number of protons present in the nucleus of an atom of an element

Question 9

Mass number

Answer 9

Is the number of protons and neutrons are present in the nucleus of an atom of an element

Question 10

Isotopes

Answer 10

atoms of the same element which have the same atomic number but the different mass number

Question 11

Octet rule

Answer 11

Atoms gain share or lose electrons in order to have eight electrons in your outside shell

Question 12

Ions

Answer 12

atoms that either lost or gained an electron and became positively or negatively charged

Question 13

Orbital

Answer 13

Region in space around the nucleus of an atom where are electrons are most likely to be found

Question 14

Energy level

Answer 14

Is one of the discrete amounts of energy that an electron has in an atom of an element

Question 15

Atomic sub level

Answer 15

Subdivision of main energy level consisting of one or more orbitals of the same energy

Question 16

Aufbau’s principle

Answer 16

Electrons always occupy the lowest available energy level

Question 17

Hund’s rule of maximum multiplicity

Answer 17

When two or more orbitals of equal energy are available to electrons that electrons always fill the orbital singling before filling them in pairs

Question 18

Pauli’s exclusion principle

Answer 18

No more than two electrons can occupy an orbital and if they do so they must have opposite spins

Question 19

Electronic configurations

Answer 19

Arrangement of electrons in an atom of an element

Question 20

Line spectrum

Answer 20

Formed when the light from the hydrogen discharge tube is passed through a prism it creates lines are definite frequency distinct colours

Question 21

Continuous spectrum

Answer 21

When white light is passed through a prism is blending of one colour into another rainbow no distinct colours

Question 22

Emission spectrum

Answer 22

Coloured lines dark background

Question 23

Absorption spectrum

Answer 23

Dark lines coloured background

Question 24

Hinesburg is uncertainty principle

Answer 24

It is impossible to measure at the same time both the velocity and the position of an electron

Question 25

Transition element

Answer 25

The one forms at least ion with a partially filled D sublevel

Question 26

Catalyst

Answer 26

A substance that can alter the rate of reaction but is not used up

Question 27

Valency

Answer 27

The number of electrons in an atom of an element will give take a share with another atom in forming chemical bonds

Question 28

Principle of the mass spectrometer

Answer 28

Positive ions are separated according to the relative masses when moving in a magnetic field

Question 29

Relative atomic mass

Average of the mass

Answer 29

Numbers of the isotopes of the element is the occur naturally taking their abundances into account expressed on a scale in which the atoms of the carbon 12 isotope have a massive exactly 12 units

Question 30

Relative molecular mass

Answer 30

The compound is the average mass of one molecule of the compound compared with 1/12 of the mass of one atom of the carbon 12 isotope

Question 31

Atomic radius

Answer 31

Defined as half the distance between the nuclei of two atoms of the same element or a joined together by single covalent bond

Question 32

First ionisation energy

Answer 32

Minimum energy required to completely remove the most loosely bound electron from one molecule of an isolated neutral gaseous item in its ground state

Question 33

Second ionisation energy

Answer 33

Is there energy required to remove an electron from an ion with one positive charge in the gaseous state

Question 34

Electronegativity

Answer 34

Of an atom is a measure of the power of attraction that an atom in a molecule has for the shared pair of electrons in covalent bond

Question 35

Ionic bond

Answer 35

Force of attraction between oppositively charge ions that have resulted from the transfer of electrons from one element to the other

Question 36

Covalent bond

Answer 36

Formed when atoms share a pair of electrons so that they satisfy the octet rule

Question 37

Polar covalent

Answer 37

Bond in which there is an equal sharing of the pair of electrons it causes one end of the bonded to be slightly positive and the other slightly negative