Unit 1: Foundation chemistry

Question 0

what is the mass no.?

Answer 0

total no. of protons and neutrons in the nucleus of one atom of the element

Question 1

Define ionisation energy

Answer 1

Energy required to remove a mole of electrons from a mole of atoms in the gaseous state

Measured in kJ mol-1

Question 2

what is the atomic no.?

Answer 2

no. of protons in the nucleus of one atom of the element

Question 3

state the 3 main fundamental particles and their mass and charge

Answer 3

particle, relative mass, relative charge:
proton , 1, +1
neutron, 1, 0
electron, very small 1/1840, -1

Question 4

Define relative atomic mass

Answer 4

Weighted average mass of all isotopes divided by 1/12 mass of one atom of carbon-12

Average mass of an atom/isotope on a scale where an atom of C12 had a mass of exactly 12g

Question 5

Define structural isomers

Answer 5

Compound with the same molecular formula but a different structural formula

Question 6

Identify a catalyst used in a catalytic converter

Answer 6

Iridium or Platinum or Palladium or Rhodium

Question 7

Hazards associated with the product solid carbon in combustion

Answer 7

Global dimming 
Exacerbates asthma 
Damages lungs
Breathing problems 
Smog/smoke etc.

Question 8

Relative molecular mass

Answer 8

Average mass of one molecule divided by 1/12th of mass of an atom of C12

Mass of a molecule on a scale whee the mass of C12 is exactly 12g

Question 9

Avogadro constant

Answer 9

Total number of particles in a mole of substance

No. Of atoms in 12g of carbon 12

6.022 x 10^23 atoms = mole

Question 10

Electro negativity

Answer 10

Power of an atom to attract the electron density in a covalent bond towards itself

Describes the way negative charge is distributed in a molecule

Question 11

Bond angles and shape names

Answer 11

Linear 180
Trigonal planar 120
Tetrahedral 109.5
Trigonal bipyramidal 120 and 90
Octahedral 90
Square Planar 90
Additional 2 per lone pair

Question 12

Bond angles for water H20 and ammonia NH3

Answer 12

Water 104.5
Ammonia 107

Due to 2 extra per lone pair

Question 13

Atomic radii definition

Answer 13

Half the distance between the centres of a pair of atoms

Question 14

Atomic radii trends

Answer 14

Decrease across a period - increased nuclear charge, same shielding, pulls electrons closer to nucleus

Increase down a group - increase in main level of electrons, outer electrons get further from nucleus

Question 15

General First ionisation energy trends

Answer 15

Increases across a period - increasing nuclear charge, same distance, same shielding, harder to remove electrons

Decreases down a group - increase in shielding, increased distance, held less strongly, easier to remove electrons

Question 16

Why do we assume that there are the same number of protons and electrons in an atom?

Answer 16

In a neutral atoms the number of electrons must be the same as the number of protons because their charge is equal in size and apposite in sign

Question 17

Isotope definition

Answer 17

Atoms with the same number is protons but different number of neutrons
Different mass numbers but same atomic number

Question 18

Explain why the ions formed in a mass spectrometer have a positive charge

Answer 18

Because they have lost electrons which are negatively charged

Question 19

What causes ions to accelerate through the mass spectrometer?

Answer 19

Positive ions are Attracted by a negatively charged plate

Question 20

What forms ions into a beam in mass spectrometry?

Answer 20

The ions pass through a series of holes or slits

Question 21

What bends the ions into a curved path in mass spec?

Answer 21

A magnetic field at right angles to their direction of motion

Question 22

What is the Schrodinger equation?

Answer 22

Solutions to this equation give the probability of finding an electron in a given volume of space called an atomic orbital

Question 23

What is activation energy?

Answer 23

Minimum energy that a particle needs in order to react
the energy (enthalpy) differed between the reactants and the transition state

Question 24

Define aldehyde

Answer 24

An organic compound with the general formula RCHO in which there is a C–0 double bond

Question 25

Define alkanes

Answer 25

A hydrocarbon with C-C and C-H single bonds only.

General formula CnH2n+2

Question 26

Define allotropes

Answer 26

Pure elements which can exist in different physical forms in which their atoms are arranged differently
E.g Diamond, Graphite, Buckminsterfullerence are allotropes of carbon

Question 27

Percentage Atom economy definition and equation

Answer 27

Describes the efficiency of a chemical reaction by comparing the total number of atoms in the product wit the total number of atoms in the starting materials

= mass desired product/total mass of reactants x 100

Question 28

Define atomic orbital

Answer 28

A region of space around an atomic nucleus where their is a high probability of finding an electron