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Flashcards in module 1 Deck (37):
1

isotope

atoms of the same element with different numbers of neutrons

2

atomic n.o

number of protons in the nucleus of an atom

3

mass n.o

number of particles (protons and neutrons) in the nucleus

4

ion

positively or negatively charged atom

5

relative isotopic mass

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

6

relative atomic mass Ar

the weighted mean mass of an atom of an element compared with 1/12 of an atom of carbon-12

7

relative molecular mass Mr

the weighted mean mass of a molecule compared with 1/12 of an atom of carbon-12

8

relative formula mass

the weighted mean mass of a formula unit (empirical formula) compared with 1/12 of the mass of an atom of carbon-12

9

amount of substance

the quantity whose unit is the mole. 'amount of substance' is a means of counting atoms.

10

the Avogadro constant Na

the number of atoms per mole of the carbon-12 isotope (6.02 x 10^23 mol^-1)

11

mole

the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon 12 isotope.

12

molar mass

the mass per mole of a substance g-mol^-1

13

empirical formula

the simplest whole number ratio of atoms present in a compound

14

molecule

a small group of atoms held together by covalent bonds

15

the molecular formula

the actual number of atoms of each element in a molecule

16

molar volume

this is the volume per mole of gas. dm^3 mol^-1
At rtp molar volume is 24.0 dm^3 mol^-1

volume(dm^3) = n.o moles x 24

volume(cm^3) = n.o moles x 24000

17

concentration

the amount of solute in mol dissolved per 1dm^3 (1000cm^3) of solution.

18

standard solution

a solution of known concentration. normally used in titrations to determine unknown information about another substance.

19

species

a type of particle that takes place in a chemical reaction

20

stochiochemistry

the molar relationship between relative quantities of substances taking part in a reaction

21

acid

a species that is a proton donor

all acids contain hydrogen, when added to water, acids release this hydrogen as H+ ions (protons)

22

base

a species that is a proton acceptor

23

alkali

a base dissolved in water, forming hydroxide ions

NaOH(s) + aq ----> Na+ (aq) + OH- (aq)

e.g. NaOH, KOH, NH3

24

salt

a chemical compound formed from an acid when a H+ ion from the acid has been replaced by a metal ion or another positive ion such as the ammonium ion NH4+

25

cation

positively charged ion

26

anion

negatively charged ion

27

hydrated

refers to a crystalline compound containing water molecules

28

anhydrous

refers to a substance that contains no water molecules

29

water of crystallisation

refers to water molecules that form an essential part of the crystalline structure of a compound

30

methyl orange
colour changes:
acid...
base...
neutral...

colour changes:
acid...red
base...yellow
neutral...orange

31

bromothymol blue
colour changes:
acid...
base...
neutral...

colour changes:
acid...yellow
base...blue
neutral...green

32

phenolphthalein
colour changes:
acid...
base...
neutral...

colour changes:
acid...colourless
base...pink
neutral...pale pink

33

oxidation number

a measure of the number of electrons that an atom uses to bond with atoms of another element

34

oxidation

loss of electrons
or
increase in oxidation n.o

35

reduction

a gain of electrons
or
decrease in oxidation n.o

36

reducing agent

a reagent that reduces (adds electrons to) another species.

37

oxidsing agent

a reagent that oxidises (takes electrons) from another species.