Atomic Structure UNIT 1

Question 0

Relative mass and charge of a neutron

Answer 0

Mass…..1

Chase……0

Question 1

Relative mass and charge of a proton

Answer 1

Mass…. 1

Charge….. +1

Question 2

Relative mass and charge of an electron

Answer 2

Mass……. 1/2000

Charge…….-1

Question 3

All atoms of the same element have the …….. Number of protons

Answer 3

SAME

Question 4

Neutral atoms have the same number of what?

Answer 4

Protons and electrons

Question 5

What makes an atom neutral

Answer 5

Having the same number of electrons and protons

Question 6

Isotopes can have different physical properties such as……. Why?

Answer 6

Different densities, rates of diffusion

Physical properties depend more on the mass of the atom

Question 7

Define relative isotopic mass

Answer 7

Mass of an atom of an isotope of an element compared with 1/12 the mass of carbon12

Question 8

Electron shells are made up of…

Answer 8

Sub-shells and orbitals

Question 9

Each electron shell is given a number called what

Answer 9

Principal quantum number

Question 10

What does it mean the energy shell is further from the nucleus

Answer 10

The higher it’s energy and the larger it’s principal quantum number

Question 11

The two electrons in each orbital spin in the…..

Answer 11

Opposite direction

Question 12

Which sub shell fills first…3d or 4s? Why?

Answer 12

4s because it has a lower energy level than 3d, even though it’s principal quantum number is bigger

Question 13

Examples of transition metals acting unusually

Answer 13

Cr and Cu donate one of their 4s electrons to the 3d sub shell, as they are happier with a more stable full or half full d sub shell

When they become ions they lose their 4s electrons before their 3d electrons

Question 14

The number of outer shell electrons decides the ………. ……..

Answer 14

Chemical properties

Question 15

Number of Outer shell electrons in group 1and 2 (s block) elements

Answer 15

1 or 2, these are easily lost to form positive ions with an inert gas configuration

Question 16

Number of electrons in groups 5,6 and 7 (p block)

Answer 16

5,6 or 7 outer electrons. They gain 1,2 or 3 electrons to form negative ions with an inert gas configuration. Groups 4-7 can also share electrons when they form covalent bonds

Question 17

Number of outer electrons in group 0 ( the inert gases)

Answer 17

Have completely filled s and p sub shells so don’t lose or gain electrons, their full sub shells make them inert

Question 18

Number of outer electrons in d block (transition metals) elements

Answer 18

2 electrons, tend to lose s and d electrons to form positive ions

Question 19

What did John Dalton describe atoms as in the 19th century

Answer 19

Solid spheres, different spheres made up different elements

Question 20

What was J J Thompson’s theory in 1897

Answer 20

He concluded from his experiments that atoms weren’t solid and indivisible. His measurements of charge and mass showed that an atom must contain even smaller, negatively charged particles-electrons . The solid sphere idea had t be changed, the new model was called the ‘plum pudding model’

Question 21

What did Rutherford show

Answer 21

That the plum pudding model was wrong

Question 22

What was rutherfords experiment

Answer 22

It was called the gold foil experiment. They fired alpha particles (which are positively charged) at an extremely thin sheet of gold. From the plum pudding model, they were expecting most of the particles to be deflected very slightly by the positive ‘pudding’ that made up most of the atom. But most of the particles passed straight through the gold atoms, very small number deflected backwards. So plum pudding couldn’t be right. Rutherford came up with the nuclear model of the atom. In this there is s tiny positively charged nucleus at the centre surrounded by a cloud of negative electrons, most of the atom is an empty space.

Question 23

What did scientists discover was wrong with rutherfords model

Answer 23

They realised that electrons in a cloud around the nucleus of an atom would quickly spiral down into the nucleus causing the atom to collapse

Question 24

What did the Bohr model propose

Answer 24

Electrons can only exist in fixed orbitals, or shells, and nowhere else

Each shell has a fixed energy

When an electron moves between shells electromagnetic radiation is emitted and absorbed

Because the energy of shells is fixed, the radiation will have a fixed frequency

Question 25

What is one of the things that makes a theory scientific

Answer 25

If it’s ‘falsifiable’. You can make predictions using the theory, then if you test the predictions and they turn out to be wrong, you know the theory is wrong

Question 26

What did scientists find wrong with the Bohr model

Answer 26

Not all the electrons in a shell had the same energy. So they refined it to include sub shells

Question 27

How did the Bohr model explain why some gases are inert

Answer 27

Bohr said that the shells of an atom can only hold fixed numbers of electrons, and that an elements reactivity is due to its electrons. So when an atom has full shells of electrons it’s stable and doesn’t react.

Question 28

Is there only one accepted model of the atom today

Answer 28

No, Bohr model is not perfect but is still widely used to describe atoms because it is simple and explains many observations from experiments, like bonding and ionisation trends. The most accurate model involves complicated quantum mechanics. Explains the direction that the electron is moving in and how they can also act aaa waves . This may be more accurate but harder to visualise, does explain some observations that can’t be accounted for by the Bohr model. Scientists use whichever model is most relevant to whatever they’re investigating.