Transition Work

Question 1

When is a measurement valid?

Answer 1

When it measures what it’s supposed to be measuring

Question 2

When is a result accurate

Answer 2

When it’s close to the true value

Question 3

What are precise results

Answer 3

When repeat measurements consistently agree with each other

Question 4

What is repeatability

Answer 4

How precise measurements are when repeated by the same person, with the same equipment and under the same conditions

Question 5

What is reproducibility?

Answer 5

How precise measurements are when taken by a different people using different equipment

Question 6

What is the uncertainty of a measurement

Answer 6

The interval within which the true value is expected to lie

Question 7

Define measurement error

Answer 7

The difference between a measured value and the true value

Question 8

What is a random error?

Answer 8

An error caused by results varying around the true value in an unpredictable way

Question 9

What is a systematic error?

Answer 9

A consist difference between the measured values and true values

Question 10

What does zero error mean?

Answer 10

A measuring instrument takes a false reading when the true value is supposed to be zero

Question 11

Which variable is changed or selected by the investigator?

Answer 11

Independent variable

Question 12

What is the dependent variable?

Answer 12

A variable measured every time the independent variable is changed

Question 13

Define a fair test

Answer 13

A test in which only the independent variable is allowed to affect the dependent variable

Question 14

What are control variables?

Answer 14

Variables that should be kept constant to avoid them affecting the dependent variable

Question 15

What does an atom consist of?

Answer 15

A nucleus contains protons and neutrons surrounded by electrons on shells

Question 16

What is the relative mass of protons

Answer 16

1

Question 17

What is the relative mass of neutrons

Answer 17

1

Question 18

What is the relative mass of electrons

Answer 18

1/1840 (very small)

Question 19

What are the relative charges of protons, neutrons and electrons

Answer 19

+1 , 0 , -1

Question 20

How do the number of protons and electrons differ in an atom

Answer 20

They’re the same as the atoms have a neutral charge

Question 21

What force holds an atomic nucleus together?

Answer 21

Strong nuclear force

Question 22

What is the atomic number of an element

Answer 22

The number of protons in the nucleus of a single atom of an element

Question 23

What is the mass number of an element?

Answer 23

Number of protons + number of neutrons

Question 24

What is an isotope?

Answer 24

An atom with the same number of protons but different number of neutrons

Question 25

What is an ion?

Answer 25

An atom with a charge

Question 26

What is the function of a mass spectrometer?

Answer 26

Accurately determines the mass and abundance of separate atoms or molecules to help us identify them

Question 27

What is a mass spectrum?

Answer 27

The output from a mass spectrometer that shows the different isotopes that make up an element

Question 28

What is the total number of electrons that each electron shell can contain?

Answer 28

2n^2 (n is the number of the shell)

Question 29

What are the first four electron sub-shells called?

Answer 29

s, p, d, f (in order)

Question 30

How many electrons can each orbital hold

Answer 30

maximum of 2

Question 31

Define the term ionisation energy and give its unit

Answer 31

The energy it takes to remove a mole of electrons from a mole of atoms in the gaseous state

Question 32

What is the unit for ionisation energy

Answer 32

kJmol^-1

Question 33

What is the equation for relative molecular mass

Answer 33

relative atomic mass = average mass of 1 molecule / (1/12 mass of 1 atom of carbon-12)

Question 34

What is relative molecular mass

Answer 34

the average mass of one molecule of a substance when when compared with 1/12 of the mass of an atom of carbon-12

Question 35

What is the equation for relative atomic mass?

Answer 35

Average mass of 1 atom / (1/12th mass of 1 atom of carbon-12)