Glossary For First Test

Question 1

Atom

Answer 1

Smallest constituent unit of ordinary matter that has the properties of a chemical element

Made up of a nucleus and a cloud of electrons

Question 2

Electron

Answer 2

Subatomic particle with a negative elementary electric charge

Question 3

Nucleus

Answer 3

Small, dense region consisting of protons and neutrons at the centre of an atom

Question 4

Ion

Answer 4

Atom/molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge

Question 5

Cation

Answer 5

A positive ion, there are fewer electrons than protons

Question 6

Anion

Answer 6

A negative ion, there are more electrons than protons

Question 7

Molecule

Answer 7

Electrically neutral group of two or more atoms held together by chemical bonds

Question 8

Electron configuration

Answer 8

Distribution of electrons of on atom/molecule amongst its atomic/molecular orbitals

Question 9

Electron shell / principal energy level

Answer 9

An orbit followed by electrons around an atom’s nucleus

Question 10

Electron sub-shell

Answer 10

Each shell is composed of one or more subshells of different symmetry which are themselves composed of separate atomic orbitals

Question 11

Atomic/molecular orbitals

Answer 11

Mathematical function that describes the wave like behavior of either one election or a pair of electrons in an atom/molecule

Question 12

Relative atomic Mass

Answer 12

The average mass of atoms of a particular element, taking into account all of its isotopes in their natural abundance

Question 13

Electronegativity

Answer 13

Chemical property that describes the tendency of an atom or a functional group to attract or pull electrons towards itself

Question 14

Metallic bond

Answer 14

Occurs as a result of electromagnetism and describes the electrostatic attractive force that occurs between conduction electrons (in the form of on electron cloud of delocalised electrons) and positively charged metal ions

Question 15

Covalent bond

Answer 15

Chemical bond that involves sharing electron pairs between atoms

The covalent bonding orbital is a linear combination of atomic orbitals and is lower in energy than those

Question 16

Sigma bond

Answer 16

Strongest type of covalent chemical bond that is formed by head-on overlapping between atomic orbitals

Question 17

Pi bond

Answer 17

Covalent chemical bond where two lobes of one involved atomic orbital overlap two lobes of the other involved atomic orbital. Each of these atomic orbitals is zero at a shared nodal plane, passing though the two bonded nuclei. The same plane is also a nodal plane for the molecular orbital of the pi bond

Question 18

Bond polarity

Answer 18

Separation of electric charge leading to a molecule or its chemical groups having on electric dipole or multiple moment

Molecular polarity is dependent on the difference in electronegativity between atoms in a compound and the asymmetry of the compound’s structure

Question 19

Delocalised electrons

Answer 19

Electrons in a molecule/ion/solid metal that are not located on a single atom or in a particular bond but are spread out over two or more atoms

Question 20

Stoichiometry

Answer 20

Whole number ratio of moles in which two substances react together to form products