C3 - Atoms, Elements and compounds Flashcards Preview

IGCSE Chemistry > C3 - Atoms, Elements and compounds > Flashcards

Flashcards in C3 - Atoms, Elements and compounds Deck (56)
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1
Q

An atom is made up of a

A

positively charged nucleus surrounded by negatively charged electrons

2
Q

The atomic number is the number of

A

protons in an atom of a particular element

3
Q

The mass number of an atom is

A

the number of protons and neutrons found in a nucleus

4
Q

What is the mass and atomic number of sodium

A

Mass number = 23

Atomic number = 11

5
Q

What sub atomic particles make up the nucleus

A

protons and neutrons

6
Q

Difference between physical and chemical changes

A

Physical changes change the appearance of a substance and not the chemical composition whilst in a chemical change one or more new substances are produced.

7
Q

What experiment shows that some chemical changes can be reversed

A

Hydrated blue copper sulfate crystal test
When heated a white powder will form (anhydrous copper sulfate) and water is lost as steam. If water is added it turns blue.

8
Q

What is the relative mass of protons, neutrons and electrons

A
proton = 1
neutron = 1
electron = 1/2000
9
Q

Another name for mass and atomic number

A

nucleon number (for mass) and proton number (for atomic)

10
Q

Hydrogen has a proton and electron but no

A

neutron

11
Q

In an atom the number of protons is equal to the

A

number of electrons

12
Q

In a periodic table the elements are arranged via

A

their atomic number

13
Q

Atoms have no

A

overall charge

14
Q

When an atom becomes charged due to losing or gaining electrons it is called an

A

ion

15
Q

If atoms lose one or more electrons in outer shell its called a

A

positive ion

16
Q

If an atom gains one or more electron in outer shell its called a

A

negative ion

17
Q

What is an isotope

A

A same element atom with same number of protons but different number of neutrons

18
Q

Isotopes have the same properties as their regular atoms because

A

they have the same number of electrons in the outer shell

19
Q

A nuclide is a

A

type of isotope that is characterized due to its distinct specific nucleus

20
Q

Electrons have fixed positions in atoms called

A

electron shells

21
Q

What is the electron configuration of an atom

A

2 electrons max on the first shell

then it’s 8 max on the next shell after that.

22
Q

The closer a shell is to the nucleus of an atom

A

the lower its energy level is

23
Q

What is the electron configuration of an atom of sodium

A

11 electrons in sodium so

2,8,1

24
Q

What is an ionic bond between

A

a metal (+) and a non-metal (-)

25
Q

Both metals and non-metals try to achieve a

A

complete outer electron shell

26
Q

Properties of non-metals

A
Poor conductors of electricity
Low melting and boiling points
Dull
Brittle
Poor conductors of heat
27
Q

Ionic bonding involves the

A

attraction between two oppositely charged ions to achieve a full outer shell of electrons

28
Q

What are the 3 ways atoms can be chemically bonded

A

Ionic bonding, covalent bonding and metallic bonding

29
Q

Covalent bonding involves bonding between

A

two non-metals to share 1 or more pairs of electrons

30
Q

Metallic bonding involves attraction between

A

positive charged metal ions and delocalized negatively charged electrons.

31
Q

What is an ionic compound

A

when millions of ions are held together by electrostatic forces between oppositely charged ions in the form of an ionic lattice

32
Q

Properties of ionic compounds

A
Cannot conduct electricity in solid form as the ions are fixed and there are no free electrons
When turned molten or dissolved in water ions are free and the electrons become delocalized allowing energy flow
High MP and BP because a lot of energy required to break the ionic bonds in each ion
Are hard (due to strong bonds) and brittle
33
Q

Ionic compounds are structured in

A

alternating positive and negative ions in the form of a giant lattice structure

34
Q

A covalent bond is the result of an

A

attraction between bonding pairs of electrons and the nuclei of an atom involved

35
Q

When atoms covalently bond they become

A

molecules

36
Q

Small covalent molecules are held by

A

strong covalent bonds

37
Q

The forces between the covalent molecules are

A

weak intermolecular forces

38
Q

Properties of small covalent molecules

A

Low BP and MP due to weak intermolecular forces
Cannot conduct electricity due to no free electron
Often gases and liquids at room temperature

39
Q

Bigger molecules in small covalent molecules have

A

more intermolecular forces so as you go down the group 7 BP and MP gets bigger

40
Q

What is an example of a double covalent bond

A

oxygen as they share 2 pairs of electrons (O2 = O2)

41
Q

What is the display formula for covalent bond of Cl2

A

Cl - Cl

42
Q

How many types of covalent bonds are there

A

3

Single double and triple bonds

43
Q

Ionic compound features

A

Volatility: Low
State at room temp: Solid
Solubility in water: High
Electrical conductivity: Low (ions not free)
Electrical conductivity in solution: High (ions are free)

44
Q

Covalent bond features

A

Volatility: High
State at room temp: Usually liquid or gas
Solubility in water: Low
Electrical conductivity: Low (no charge)
Electrical conductivity in solution: Low (no charge)

45
Q

What are giant covalent structures

A

Huge number of non-metal atoms and in regular repeating lattices

46
Q

3 examples of giant covalent structures

A

Diamond, graphite and silicon dioxide

47
Q

Properties of giant covalent bonds

A

One single molecule
High BP and MP because loads of energy required to break every individual strong bond
Don’t conduct electricity even when molten (except graphite)

48
Q

What are allotropes

A

Different forms or structures of the same element i.e Allotropes of carbon are diamond, fullerenes and graphite

49
Q

Properties of graphite

A

Each carbon atom is bonded to 3 other carbon atoms
They are hexagonal shape and within layers held by weak intramolecular forces.
Layers are soft so slide over each other
Graphite is soft
Used as a pencil and is a lubricant
Has free electrons so conducts heat and electricity

50
Q

Properties of diamond

A

Very hard (used for cutting tools or to cut materials)
Each carbon atom is bonded to 4 other carbon atoms
Has high melting point
Does not conduct electricity as no free electrons

51
Q

A solid metal consist of

A

Giant structure of atoms in a regular pattern

52
Q

How is a metal held in a regular structure

A

The metal atoms give up its electrons to share with other metal atoms. It forms a sea of delocalized electrons.
The metal atoms become positively charged as they lost electrons and are electrostatically attracted to the negatively charged electrons which holds the metal together in a regular pattern

53
Q

Why are alloys harder to break than pure metals

A

Since alloys consist of two or more different metallic elements the atoms are different sizes which disrupts the regular pattern and makes it harder to slide over the layers.

54
Q

What are the layers in graphite called

A

graphene

55
Q

Graphene can be shaped into tubes and spheres called

A

fullerenes

56
Q

Use of fullerenes

A

Transport drugs
Industrial catalyst
Nanotubes