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Flashcards in Key Concepts of Chemistry Deck (38):
1

Describe the Pre 1900 model.

Tiny solid spheres that could not be divided.

2

Describe the 1897 Plum Pudding model.

A ball of positive charge with negative electrons embedded in it.

3

Describe the 1909 Nuclear model.

Positively charged nucleus in the centre surrounded by negative electrons.

4

Describe the 1913 Bohr model.

Electrons orbit the nucleus at specific distances.

5

What did the alpha particle experiment prove?

That the mass concentrated at the centre of the atom with large empty spaces surrounding.

6

Why is James Chadwick important?

He provided the evidence to existence of neutrons within the nucleus.

7

What is the relative charge and mass of protons?

R/C = +1
MASS = 1

8

What is the relative charge and mass of electrons?

R/C = -1
MASS = Very small

9

What is the relative charge and mass of neutrons?

R/C = 0
MASS = 1

10

What is the mass number of an element?

The sum of the protons and neutrons in the nucleus.

11

What is the atomic number of an element?

Number of protons in an atom.

12

What are isotopes?

Atoms with the same number of protons and a different number of neutrons.

13

How do you calculate relative abundance?

(% iso 1 x mass of iso 1) + (% of iso 2 x mass of iso 2)
/ 100

14

Position of metals on the periodic table:

To the left.

15

Position of non-metals of the periodic table:

To the right.

16

Properties of metals:

POSITIVE IONS.
- high melting and boiling points
- good conductors of electricity
- malleable
- ductile

17

Properties of non-metals:

NEGATIVE IONS.
- insulators
- low melting and boiling points

18

How does Mendeleev's Periodic Table differ from the modern day version?

MENDELEEV'S VERSION:
- arranged in order of atomic weight.
- some elements were undiscovered
- inappropriate grouping

19

What is Metallic Bonding?

Giant structure of where outer shell electrons are delocalised.
This creates strong forces.

20

Properties of Metallic Bonds:

HIGH MELTING AND BOILING POINTS:
- due to strong metallic bonds.
PURE METALS CAN BE BENT AND SHAPED:
- atoms arranged in layers can slide over each other.
GOOD CONDUCTORS OF ELECTRICITY AND HEAT:
- delocalised electrons transfer energy.

21

What is Covalent Bonding?

Atoms sharing pairs of electrons, shown by:
(SMALL MOLECULES)
- dot and cross diagrams
- 2D with bonds
- 3D ball and stick
(GIANT COVALENT STRUCTURES)
- polymers/hydrocarbon chains.

22

Properties of Covalent Bonds:

LOW MELTING AND BOILING POINTS:
- small amounts of energy needed to overcome the intermolecular forces.
POOR CONDUCTORS OF ELECTRICITY AND HEAT:
- no free electrons to transfer energy.

23

What is Ionic Bonding?

Transfer of electrons so all atoms have a noble gas configuration.

24

Properties of ionic bonding:

HIGH MELTING AND BOILING POINTS:
- lot of energy needed to break bonds.
DO NOT CONDUCT ELECTRICITY WHEN SOLID:
- ions held in fixed positions in lattice.
BUT CONDUCT ELECTRICITY WHEN MOLTEN:
- lattice breaks apart and ions are free to move.

25

What is the difference between anions and cations?

Cations and positively charged ions, whereas anions are negatively charged.

26

Structure of Ionic Compounds:

- lattices have regular atom arrangements.
- held by strong electrostatic forces between oppositely charged atoms.
- forces act in all directions in the lattice.

27

what does the ending '-ate' show about a compound?

The compound contains oxygen.

28

Properties of Diamond:

USED FOR CUTTING TOOLS AND JEWELLERY
- very hard
- v high melting point
- doesn't conduct electricity
- rigid structure
- strong covalent bonds
- no delocalised electrons

29

Properties of Graphite:

USED FOR ELECTRODES AS THEY ARE INERT:
- slippery
- layers can slide over
- v high melting point
- conducts electricity
- strong covalent bonds
- delocalised electrons between layers

30

Properties of Graphene:

- excellent conductor
- very strong
- contains delocalised electrons
- strong covalent bonds

31

What are Fullerenes?

Hexagonal rings of carbon atoms with hollow shapes. Can also have rings of 5 or 7 atoms.

32

Why does diamond, graphite and silicon dioxide have a high melting point?

Lots of energy is needed to break strong, covalent bonds.

33

What is Mr?

The sum of RAMs of atoms.
sum of Mr of the reactants = sum of Mr of the products

34

What is conservation of mass?

No atoms are lost or made during a chemical reaction.
mass of the product = mass of the reactants.

35

What is Avogadro's constant?

One mole of any substance will contain the same number of particles, atoms, molecules or ions.
AVOGADRO'S CONSTANT = 6.02 x 10^23

36

Concentration equation?

conc (g/dm^3) = mass (g) / volume (dm^3)

37

What does greater mass show in concentration?

higher concentration.

38

What does greater volume show in concentration?

lower concentration.