Definitions

Question 1

mass number

Answer 1

total number of protons +neutrons in an atom

Question 2

isotopes

Answer 2

atoms of the same element with same atomic number but different mass numbers

Question 3

acid (Brønsted and Lowry)

Answer 3

a proton donor

Question 4

base

Answer 4

a proton acceptor

Question 5

alkali

Answer 5

a water-soluble base eg. CaO

Question 6

strong acid

Answer 6

acid that ionises completely (100%)

Question 7

weak acid

Answer 7

acid that ionises partially (

Question 8

mole

Answer 8

a Si unit which measures the number of particles in a specific substance

Question 9

Avogadro’s number

Answer 9

6.02*10^23

Question 10

relative atomic mass

Answer 10

average mass of an atom of element based on its isotopic composition relative to carbon-12

Question 11

relative molecular mass of compound

Answer 11

sum of the relative atomic masses of atomic species in formula

Question 12

molar mass of molecule

Answer 12

mass of all the atoms in a molecule in g/mol

Question 13

physical change

Answer 13

no new substance formed
reversible
changes of state - melting, evaporation, condensation, solidification
breaking glass
dissolving solids in water

Question 14

chemical change

Answer 14

new substance formed
not easily reversible
energy change occurs
burning Match
cooking egg
rusting

Question 15

molecules

Answer 15

consists of two or more atoms combined together

Question 16

compounds

Answer 16

consists of two or more elements combined together chemically with at least two different elements

Question 17

mixtures

Answer 17

two or more different substances not chemically combined

Question 18

metalloid

Answer 18

element with properties of both metals and non metals

Question 19

heterogenous (insoluble)

Answer 19

sedimentation solid to liquid
recantation solid to liquid
filtration solid to liquid
separating funnel liquid to liquid

Question 20

homogenous (soluble)

Answer 20

evaporation
distillation 
crystallisation 
fractional distillation
sublimation 
chromatography

Question 21

from left to right
reactivity:
electro negativity:
atomic radius:
bonding/ionic:

Answer 21

high to low to high/low
increases
decreases
from bonding/ionic to covalent/ionic

Question 22

down the periodic table

Answer 22

metallic activity increased
atomic radius increase
EN decreases

Question 23

Polar Bonds

Answer 23

when a bonding pair of electrons is shared unequally and is not distrusted uni formally between the nuclei of two atoms, a polar bond is formed
when atoms have > 0.4 difference in EN and

Question 24

polar molecules

Answer 24

molecules containing only non-polar bonds will be non-polar molecules

in a polar molecule one end of the molecule is slightly negative and one end is slightly positive

Question 25

intermolecular forces

Answer 25

secondary bonding between molecules determines some physical properties: melting point possible solvents three types: dispersion forces (vanderwaals force) dipole-dipole hydrogen bonding

Question 26

dispersion forces

Answer 26

operate between ALL types of molecules only force of attraction between non polar molecules ``` influenced by: number of atoms number of electrons polarity or non polarity of the molecule(shape) size of the molecule ``` very weak ELECTRONS ARE ALWAYS MOVING IN A COVALENT BOND AND ARE MOVING ABOUT BOTH ATOMS THUS TEMPORARY DIPOLES ARE FORMED DUE TO TEMPORARY DIPOLE FORMED IN ONE MOLECULE, THE ELECTRONS OF NEARBY MOLECULES WILL ADJUST TO FORM TEMPORARY DIPLES (INDUCED DIPOLES)

Question 27

dipole dipole forces

Answer 27

only between polar molecules polar bonds are present permanent dipoles higher mp and bo than similar non polar molecules

Question 28

hydrogen bonding

Answer 28

special case of dipole dipole reactions much stronger than dipole dipole molecule will have a H atom covalently bonded to a very electronegative atom H - N H - O H - F very large fractional charges very strong attraction between the molecules THE LARGE POSITIVE FRACTIONAL CHARGE ON A H ATOM COVALENTLY BONDED TO A VERY LARGE EN F ATOM IS ATTRACTED TO TJE NEGATIVE FRACTIONAL CHARGE ON A F ATOM ON A NEIGHBOURING MOLECULE

Question 29

solute

Answer 29

the minor component in the solution, is being dissolved

Question 30

solvent

Answer 30

the liquid in which a solute is dissolved in

Question 31

strong and weak bases

Answer 31

strength of base is determined by production of OH ions strong bases dissociate completely NaOH +aq = Na+ +OH- weak bases dissociate partially NH3 + h2o >

Question 32

physical properties of bases

Answer 32

``` bitter soapy generally colourless can conduct electricity reacts with indicators to give characteristic colours ``` turns yellow in methyl orange pink in phenolphthalein blue in bromythol blue

Question 33

metallic oxides

Answer 33

generally basic oxides | if water soluble, form alkaline solution

Question 34

non metallic oxides

Answer 34

acidic oxides

Question 35

Properties of acids

Answer 35

``` be in form solid liquid or gas sour taste do not conduct electricity in pure form need to add water for electrical conductivity (ions must be formed) Covalent bonding and molecular structure means low melting and low boiling pints detected with indicators methyl orange - pink ```

Question 36

aim of titration a

Answer 36

The purpose of a titration experiment is to discover the concentration of an unknown acid or base, by neutralizing it with a measured quantity of a base or acid solution whose concentration is known. In titrations, the known solution is the titrant and the unknown solution is the analyte.