Science Assessment 2 2024 Revision - Chemistry

studied byStudied by 2 people
5.0(1)
Get a hint
Hint

compound

1 / 39

flashcard set

Earn XP

Description and Tags

Revision from the "Don't Over React" topic.

40 Terms

1

compound

when two or more elements are chemically combined.

New cards
2

element

when two of the same atoms join together.

New cards
3

molecules

when two DIFFERENT atoms join together.

New cards
4

why do elements join?

to become stable + achieve full outer shell.

New cards
5

ionic compounds

the transferring of electrons between a chemical compound.

New cards
6

what type of substances are ionic compounds between?

metals and nonmetals

New cards
7

covalent compounds

the sharing of electrons between a chemical compound.

New cards
8

what type of substances are covalent compounds between?

non-metals

New cards
9

polyatomic elements

when a lot of atoms join (e.g. sulphate, hydroxide, carbonate, phosphate etc.)

New cards
10

pH scale

ranges from 1-14, with 7 being in the middle/neutral. as you go down, the acidity increases.

New cards
11

base

anything with OH (hydroxide) ions.

New cards
12

indicators used to test the acidity or alkalinity of a substance:

  • litmus paper

  • universal indicator

  • using a pH probe

New cards
13

characteristics of acids:

  • taste sour

  • need to be dissolved in water in order to act as an acid

  • have a pH value less than 7

  • are very soluble in water

  • changes the colour of indicators

  • contain hydrogen atoms that form H+ ions when acid is dissolved in water.

New cards
14

characteristics of bases

  • tastes bitter

  • pH ranges from 8-14

  • soapy to touch

  • releases hydroxide ions

  • conducts electricity

  • changes the colour of indicators

New cards
15

physical changes

change in the physical structure only, not chemically. no new product/substance has been formed. most of the physical changes can be reversed (e.g. the states of matter with water).

New cards
16

chemical change

change in the chemical composition/structure. generally irreversible and forms new product(s) (e.g. burning paper which turns into ash).

New cards
17

law of conservation of mass

mass cannot be created or destroyed, only transferred. Mass of reactants also needs to equal to mass of products.

New cards
18

exothermic reaction

a reaction or process that gives off heat.

New cards
19

endothermic reaction

a reaction or process that takes in thermal energy from its environment to either make or break the chemical bonds between atoms.

New cards
20

activation energy

minimum energy required to start a chemical reaction.

New cards
21

decomposition reaction

anything breaking/decomposing (corrosion, rusting)
equation is below:

AB —> A + B

New cards
22

combination reaction

anything combining
A + B —> AB (e.g. H2 + O2 = 2H2O)

New cards
23

H2SO4

sulphuric acid

New cards
24

HNO3

nitric acid

New cards
25

HCl

hydrochloric acid

New cards
26

CH3COOH

acetic acid

New cards
27

NaOH

sodium hydroxide

New cards
28

NH4OH

ammonium hydroxide

New cards
29

acid + metal reaction (or redox reaction but you don’t need to know that)

a salt + hydrogen

New cards
30

acid + base reaction (neutralisation reaction)

a salt + water

New cards
31

carbonates are normally what?

normally metals

New cards
32

acid + metal carbonates reaction

carbon dioxide + a salt + water

New cards
33

combustion reaction

anything being burned basically (but it will have oxygen and will produce carbon dioxide and water) so it’s fuel + O2 —> CO2 + H2O

New cards
34

test for hydrogen and explain

pop test - where if fire is put over the top of a test tube and it produces a distinctive ‘pop’ sound, that means that hydrogen is present.

New cards
35

test for carbon dioxide and explain

lime water test which involves air being funnelled into lime water and if the lime water turns into a milky white colour, then the gas is carbon dioxide.

New cards
36

indicator that there is hydrogen present?

when there is a distinctive “pop” sound

New cards
37

indicator that there is carbon dioxide present?

when the lime water turns into a milky white colour

New cards
38

precipitation reaction

when two clear solutions are mixed together, the formation of a solid is called a precipitation reaction. the formula is aqueous + aqueous —> solid (or precipitate) + aqueous

New cards
39

rate of reaction

the time taken for a reaction to occur

New cards
40

factors affecting rate of reaction

  • temperature/heat

  • surface area

  • catalysts

  • concentration of substance

New cards

Explore top notes

note Note
studied byStudied by 178 people
... ago
5.0(3)
note Note
studied byStudied by 10 people
... ago
5.0(1)
note Note
studied byStudied by 36 people
... ago
5.0(1)
note Note
studied byStudied by 164 people
... ago
5.0(3)
note Note
studied byStudied by 18 people
... ago
5.0(1)
note Note
studied byStudied by 87 people
... ago
5.0(1)
note Note
studied byStudied by 42 people
... ago
5.0(2)
note Note
studied byStudied by 234 people
... ago
5.0(1)

Explore top flashcards

flashcards Flashcard (465)
studied byStudied by 29 people
... ago
5.0(1)
flashcards Flashcard (108)
studied byStudied by 8 people
... ago
5.0(1)
flashcards Flashcard (55)
studied byStudied by 7 people
... ago
5.0(1)
flashcards Flashcard (45)
studied byStudied by 28 people
... ago
5.0(1)
flashcards Flashcard (136)
studied byStudied by 5 people
... ago
5.0(1)
flashcards Flashcard (49)
studied byStudied by 37 people
... ago
4.7(3)
flashcards Flashcard (41)
studied byStudied by 75 people
... ago
5.0(2)
flashcards Flashcard (57)
studied byStudied by 25 people
... ago
5.0(1)
robot