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Combined Science IGCSE > Chemistry > Flashcards

Flashcards in Chemistry Deck (59)
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1

Which changes of state need energy?

Melting, evaporating and sublimation

2

What is an atom?

Simplest thing that can exist on its own

3

What is a molecule?

2 or more atoms joined together by covalent bonds

4

What is an ion?

Charged particle

5

What is a mixture?

2 or more substances not chemically joined together

6

Describe the structure of the atom

Nucleus that contains protons and neutrons with electrons in shells orbiting it

7

What is the mass of a proton? neutron? electron?

P= 1, n = 1, e 1/1840 or negigible

8

What are the charges on a proton? neutron? electron?

p = +, n = 0, e = -

9

What does the proton number (atomic number) tell you?

Number of protons (which equals the number of electrons in an atom)

10

How do you work out the amount of neutrons?

Mass number - atomic number

11

How is a positive ion formed? What does this happen in?

Lose an electron - metals

12

How is a negative ion formed?

Gain an electron - non metals

13

What happens in an ionic bond?

Electrons are given from metals to non-metals

14

What happens in a covalent bond?

Electrons are shared between non-metals

15

Which is the stronger bond covalent or ionic?

Ionic

16

What are the differences between ionic and covalent compounds?

Ionic have higher mpt and bpt, are soluble in water, conduct electricity when molten, not volatile (do not evaporate easily)

17

What does exothermic mean?

Gives out heat or energy

18

What does endothermic mean?

Takes in heat

19

In a chemical reaction what happens?

Bonds broken (endothermic) then new bonds made (exothermic)

20

What is loss of oxygen in a reaction called?

Reduction

21

What is gain of oxygen in a reaction called?

Oxidation

22

In the reaction
Ca0 + Mg = MgO + Ca
What was oxidised and what was reduced?

Ca = reduced
Mg = oxidised

23

What does the group number on the periodic table tell you?

Number of outer electrons

24

What are group 1 called?

Alkali metals

25

What happens as you go down group 1?

More reactive, less dense, lower mpt, less dense

26

What are group 7 called?

Halogens

27

What happens as you go down group 7?

Less reactive, more dense (more solid), darker colour

28

Will a reaction occur?
Sodium chloride + iodine

No as Iodine is less reactive than chlorine

29

Will a reaction occur?
Sodium chloride + fluorine

Yes as fluorine is more reactive than chlorine

30

What are the properties of transition metals

High density, high mpt, conductors, coloured compounds, used as catalysts