defintions

Question 1

I what is an ionic bond

Answer 1

electrostatic attraction between oppositely charged ion

Question 2

what is a homologous series

Answer 2

a family of organic compounds that have the same general formula and similiar chemical properties

Question 3

what is disproportionation

Answer 3

when an element is oxidised and reduced in the same chemical reaction

Question 4

what is a dative covalent bond

Answer 4

a covalent bond formed when one atom provides both of the shared electrons

Question 5

What is the relative atomic mass of an element

Answer 5

the average mass of an atom compared to 1/12 of the mass of an atom of carbon-12

Question 6

What is the relative formula mass of an element

Answer 6

average mass of a molecule or formula unit compared to 1/12 of the mass of an atom of carbon-12

Question 7

what is the relative isotopic mass of an element

Answer 7

the mass of an atom of an isotope of an element compared to the mass of 1/12 of the mass of an atom of carbon-12

Question 8

what is the relative molecular mass of an element

Answer 8

average mass of a molecule compared to 1/12 of the mass of an atom of carbon-12

Question 9

What does the mass number tell you

Answer 9

total number of protons and neutrons

Question 10

What is the molecular formula

Answer 10

Actual number of atoms of each element present in a molecule

Question 11

what is a standard solution

Answer 11

a solution that has a precisely known concentration

Question 12

What is an alkali

Answer 12

soluble base that releases OH- ions in aqueous solution

Question 13

what is a ionic crystal

Answer 13

giant lattice of ions that forms because ions are electrostatically attracted in all directions to ions of opposite charge

Question 14

what is a dipole

Answer 14

a difference in charge between the two atoms caused by a shift in electron density in the bond

Question 15

what causes permanent dipole -dipole interactions

Answer 15

the positive and negative dipole causes a weak electrostatic force of attraction between molecules

Question 16

how do hydrogen bonds form

Answer 16

hydrogen is covalently bonded to nitrogen , hydrogen or oxygen
hydrogen has a high charge density as its a small molecule and the elements it can bond to are very electronegative

Question 17

why is ice more dense than water

Answer 17

hydrogen bonds make the molecules longer so more further apart

Question 18

what is the behaviour of simple covalent compounds

Answer 18

insoluble in water because most molecules are non polar
low melting and boiling points because of weaker intermolecular forces
dont conduct electricity because most molecules are uncharged

Question 19

what is the enthalpy of combustion

Answer 19

enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditons

Question 20

what is the enthalpy change of reaction

Answer 20

enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical reaction

Question 21

what is the enthalpy change of formation

Answer 21

the enthalpy change that takes place when 1 mole of a compound of formed from its constituent elements

Question 22

what is hess law

Answer 22

if a reaction can take place by more than one route and the initial and final products are the same then the total enthalpy is the same