unit 1:chemical changes and structure

Question 1

shared pairs of electrons from both atoms forming the covalent bond

Answer 1

bonding electrons

Question 2

the term used to describe the mechanism by which atoms are held together

Answer 2

chemical bonding

Question 3

what describes the way in which atoms , ions or molecules are arranged

Answer 3

chemical structure

Question 4

what is formed when two atoms share electrons in their outer shell to complete the filling of that shell

Answer 4

covalent bond

Question 5

the term used to describe half the distance between the nuclei of two bonded atoms of an element

Answer 5

covalent radius

Question 6

used to describe electrons , in metallic bonding , that are free from attachment to any one metal ion and are shared amongst the entire structure

Answer 6

delocalised

Question 7

7 molecules with only two atoms e.g. N2 , O2 , F2 , Cl2 , Br2 , I2 , H2

Answer 7

diatomic

Question 8

an atom or molecule in which a concentration of positive charges is separated from a concentration of negative charge

Answer 8

dipole

Question 9

a measure of the attraction that an atom involved in a bond has for the electrons of the bond

Answer 9

electronegativity

Question 10

molecules of pure carbon constructed from 5- and 6- members rings combined into hollow structures. The most stable contains 60 carbon atoms in a shape resembling a football

Answer 10

fullerenes

Question 11

the strongest intermolecular force , contain a hydrogen atom bonded to and atom of stingily electronegative element such as fluorine , oxygen or nitrogen , and a highly electronegative atom on a neighbouring molecule

Answer 11

hydrogen bonds

Question 12

the term given to those which attract atoms and molecules together. they are weaker than chemical bonds. also known as van service Waals forces.

Answer 12

intermolecular forces

Question 13

a half equation , either an oxidation or a reductions , which in combination of the opposite type , can be part of a complete redox equation

Answer 13

ion-electron equations

Question 14

a bond between atoms with substantially different electronegativity , which results in the formation of positive and negative ions (with the negative ion having the higher electronegativity)

Answer 14

ionic bond

Question 15

the energy required to remove one mole of electrons from one mole of the atoms in the gaseous state

Answer 15

ionisation energy

Question 16

this means having the same arrangement of electrons. for example the noble gas neon , a sodium ion (Na+) and a magnesium ion (Mg2+)

Answer 16

isoelectronic

Question 17

a regular 3D arrangement of particles in space. the term is applied to metal ions in a solid , and to positive and negative ions in an ionic solid

Answer 17

lattice

Question 18

the forces of attraction which result from the electrostatic attraction between temporary dipoles and induced dipoles caused by movement of electrons in atoms and molecules

Answer 18

london dispersion forces (LDF’s)

Question 19

are fluids which mix or dissolve in each other in all proportions

Answer 19

miscible

Question 20

a covalent bond between atoms with the same or very similar electronegativity, which results in an equal sharing of the bonding electrons between the atoms

Answer 20

non-polar (or pure) covalent bond

Question 21

a loss of electrons by a reactant in any reaction

Answer 21

oxidation

Question 22

a substance which accepts electrons

Answer 22

oxidising agent

Question 23

the regular recurrence of similar properties when the elements are arranged in order of increasing atomic number

Answer 23

periodicity

Question 24

additional intermolecular forces of attraction which exist between polar molecules. stronger than LDF’s for molecules with similar numbers of electrons

Answer 24

permanent dipole to permanent dipole interactions (PD-PD interactions)

Question 25

a covalent bond between atoms of different electronegativity , which results in an uneven distribution of electrons and a partial change along the bond

Answer 25

polar covalent bond

Question 26

a substances physical and chemical characteristics. these are often a reflection of the chemical bonding and structure of the material

Answer 26

properties

Question 27

a substance which donates electrons

Answer 27

reducing agent

Question 28

a gain of electrons by a reactant in any reaction

Answer 28

reduction

Question 29

the resistance to flow that is exhibited by all liquids

Answer 29

viscosity

Question 30

when both atoms have the same electronegativity, bonding electrons are equally shared , mostly in elements but can also be found in compounds ( if the atoms have the same electronegativity)

Answer 30

non-polar bonds

Question 31

when atoms have different electronegativities , bonding electrons are not shared , the atom with higher electronegativity has more share of electrons , only found in compounds

Answer 31

polar bonds