Week 1 - Atomic Structure

Question 1

What is an atom?

Answer 1

Are the fundamental building blocks for everything.
Can’t see them.
Everything is made of atoms - all matter/physical substances.

Question 2

What did Dalton believe about atoms?

Answer 2

That atoms are unique to each element in their size and mass.
That matter is composed of particles called atoms.
That particles can’t be divided any further.

Question 3

What is an element?

Answer 3

It is a specific type of atom.
They are pure substances - only made of one/the same thing.
Cant be chemically broken down into different forms.
Each element has atoms of their own unique size and mass.

Question 4

What is a molecule?

Answer 4

A group of different atoms chemically bonded together.

Question 5

What is a chemical reaction?

Answer 5

A rearrangement of atoms.

Question 6

What is a compound?

Answer 6

Chemically bonded combination of elements - they combine in fixed proportions.
E.g. h2o.
E.g. sodium chloride

Question 7

What is a mixture?

Answer 7

A physical combination of 2 or more atoms, but they are not chemically bonded together.
E.g. barium sulphate.

Question 8

How many elects occur in nature?

Answer 8

92

Question 9

How many elements do living organisms contain?

Answer 9

20

Question 10

Who created the periodic table?

Answer 10

Medeleev.

Question 11

What does the period table consist of?

Answer 11

All elements.

Question 12

How are the elements arranged in the periodic table?

Answer 12

In periods and groups.
Periods are the rows - left to right.
Groups are the columns - top to bottom.
Elements are arranged in order of increasing atomic mass, left to right.

Question 13

What will each row (period) have in common?

Answer 13

Similar chemical properties.

Question 14

What will each column (group) have in common?

Answer 14

Certain characteristics, e.g. reactivity.

Question 15

What does each element in the periodic table have on it?

Answer 15

An atomic mass.
An atomic number.

Question 16

Why is tungsten often used in x-ray tubes?

Answer 16

It is extremely hard to melt.
Due to a very high melting point.

Question 17

What was the original atomic structure model, and who made it?

Answer 17

Plum pudding model.
JJ Thompson.

Question 18

What does the plum pudding model suggest about atomic structure?

Answer 18

That there are positive and negative charges which mix together in the middle of the atom - giving an overall neutral charge.

Question 19

How did JJ Thompson discover and create the plum pudding model of atomic structure?

Answer 19

He used a negative cathode ray tube, and fired electrons onto a positively charged anode.
This caused the material behind to fluoresce (showing they passed through).

Question 20

However a new atomic model structure came about -
Who created this new model and what is it called?

Answer 20

Rutherford.
Planetary model.

Question 21

What does Rutherford’s planetary model suggest?

Answer 21

That there is a nucleus in the middle of the atom - made up of neutrons and positive protons.
Then all around, in shells, are negatively charged electrons (arranged at certain energy levels).

Question 22

Where is most of the mass in an atom?

Answer 22

The nucleus

Question 23

How can an atom be neutral?

Answer 23

The atom needs the same number of protons as electrons.

Question 24

What charge, location and mass does a proton have?

Answer 24

Charge - +1
Location - the nucleus
Mass - 1.673 x10 to the power of -27
(Is the largest/heaviest subatomic particle -0 but pretty much the exact same as a neutron)

Question 25

What charge, location and mass does a neutron have?

Answer 25

Charge - no charge Location - the nucleus Mass - 1.675 x10 to the power of -27 (Is in the middle)

Question 26

What charge, location and mass does an electron have?

Answer 26

Charge - -1 Location - in shells that orbit the nucleus Mass - 9.109 x10 to the power of -31 (Are the smallest/lightest subatomic particle)

Question 27

What is matter? And what units does matter have?

Answer 27

Mostly empty space. Units of atomic mass units (not kg), as everything is very small. There is mostly empty space in an atom

Question 28

What was Rutherfords experiment to find atomic structure?

Answer 28

He believed alpha particles are made of 2 protons and 2 neutrons - giving an overall charge of 2 (2 positive protons) - e.g. helium. Rutherford believed he found that when alpha particles were fired at an atom, that they either fired straight through if they don’t hit anything (as is mostly empty matter space), or if they hit the nucleus then they bounce of/deflect in different directions. These were with gold foil experiments.

Question 29

There is a strong nuclear force in atoms. What does this do and mean?

Answer 29

It helps the atom stay together. It works by the positive proton charges repel each other, then the neutrons acting as a buffer/spacer.

Question 30

A nuclide is the layout of an atom - shows its symbol, atomic mass and atomic number. It is specific to each element.

Question 31

What is atomic mass?

Answer 31

The total number of protons and neutrons in the nucleus.

Question 32

What is atomic number?

Answer 32

The number of protons. Which is therefore essentially the number of electrons too as they need to be the same to balance the atom and not be an ion.

Question 33

Do electrons make a big difference to atomic mass and why?

Answer 33

They aren’t necessarily included, because they are so small that they don’t really make a difference.

Question 34

What is the atomic number for lead?

Answer 34

82

Question 35

What is the atomic number for tungsten?

Answer 35

74

Question 36

What is the atomic number for molybdenum?

Answer 36

42

Question 37

What is the atomic number for copper?

Answer 37

29

Question 38

What is the atomic number for barium?

Answer 38

56

Question 39

What is the mass number and atomic number for tungsten (W)?

Answer 39

Mass number - 184 (protons + neutrons) Atomic number - 74 (protons / electrons) Number of protons - 74 Number of electrons - 74 Number of neutrons - 110

Question 40

What is an isotope?

Answer 40

A similar version of an element, that has the same number of protons, but a different number of neutrons. So still has the same atomic number. But has a different atomic mass.

Question 41

What is abundance?

Answer 41

The average mass of an element. The average mass number across all isotopes.

Question 42

What location are electrons in, in the atom?

Answer 42

They orbit the nucleus in shells - 3D view - all electrons.

Question 43

What does electrons being in specific shells mean?

Answer 43

That they don’t collide with other electrons.

Question 44

What do the different shells mean?

Answer 44

They have different capacity levels/levels of potential energy. The shells have defined energy levels.

Question 45

How are the shells and their energy levels organised?

Answer 45

The shells further out have more potential energy - can hold more electrons. There are max capacity levels at each shell, as shells go further out they increase capacity. You can’t have free electrons not on a shell. The inner shells have to fully fill first,then fill up as you go further out - so outmost shells may not always fil up completely.

Question 46

What are the shells called, and what are their capacities?

Answer 46

K = shell number 1 = max number of electrons is 2. L = shell number 2 = max number of electrons is 8. M = shell number 3 = max number of electrons is 18. N = shell number 4 = max number of electrons is 32 To work out max number of electrons = 2n squared with n being the shell number.

Question 47

What is an ion?

Answer 47

An unbalanced atom (different amounts of protons and electrons in it).

Question 48

What’s a negative ion?

Answer 48

It is called an anion. The atom has gained an electron.

Question 49

What’s a positive ion?

Answer 49

Called a cation. The atom has lost an electron.

Question 50

True or false - You should assume an atom is neutral and balanced unless told otherwise (Equal number of protons and electrons)

Answer 50

True

Question 51

What is binding/ionisation energy?

Answer 51

There is a force of attraction between the positive nucleus and negative electrons in the shells. They attract to each other (not repel). Binding energy is the energy needed to remove an electron from its shell/atom. (Which is needed for an x-ray). The amount of binding energy needed depends on how many positive protons are in the nucleus, and how close it is to the electron needing to be taken (depends on the strength of that attraction force).

Question 52

What happens to the atom is binding energy is overcome and an electron is removed from its shell in the atom?

Answer 52

The atom is now said to be ionised. It has had a change in its overall charge.

Question 53

What is binding energy measured in?

Answer 53

Electron volts (eV)

Question 54

True or false - For a specific given element and shell, every electron has the same binding energy

Answer 54

True

Question 55

In what 2 ways can an atom be ionised?

Answer 55

With x-rays. Or with electrons.

Question 56

Ionisation of atoms can only occur and remove shell bound electrons if…

Answer 56

… they have enough energy to overcome the binding energy of the whole atom.

Question 57

What can ionisation result in / make the electron go where?…

Answer 57

The electron in the shells can be fully ejected, and then the exiting electron can be deflected out, e.g. after hitting that.

Question 58

What negative outcome may occur in ionisation, to do with electrons being ejected?

Answer 58

The knocked electrons may not have enough force to be fully ejected, but only climb up to a higher shell level - this is bad in x-rays as it can produce a lot of heat (infrared radiation).