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Flashcards in Atomic Structure Deck (33)
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1
Q

What is the history of the atom?

A

[Robert Boyle]
- Matter was made up of tiny particles that cannot be subdivided and particles made up different compounds

  • Particles were in solids, liquids and gases. Forces between particles made materials solid.

[John Dalton]
>Came up with idea of particles. Particles are in fixed positions in solid but free to move liquids and gases.
>Atoms were indivisible and in-destructive
>All atoms of an element are identical and have the same mass and are identical and have same chemical properties
>Atoms of different elements have different masses (atomic weights) and different chemical properties
> Atoms react to form compound atoms, known as molecules

[Joseph John Thompson]
> Atoms contained electrons
> Proposed that atoms could be divided into smaller atoms
> Electrons have very small mass, about one two-thousandths of the mass of a hydrogen atoms. They are negatively charged
> Said that the sphere of positive charge cancelled the negatively charged electrons making the atom neutral.
> Came up with the plum-pudding model

[ Rutherford]
> Came with the idea that the mass of the atom is not evenly spread
> Mass is concentrated in the centre known as the nucleus
> Rutherford calculated the diameter of the nucleus to be 10^-14
> All positive charged is contained in the nucleus
> Electrons circulate the rest of the atom, being kept apart from repulsion of negative charge

[Mosley and Rutherford]
Nucleus contained positive charged particles called protons and protons determined the position on the periodic table
Protons make half the mass of the atom

[Chadwick]
Identified what are known as neutrons and they have no charge
They have the same mass as protons

[Niels Bohr]
>Electrons orbit what are known as energy levels
>Energy levels are quantised
>Electrons occupy set energy levels

2
Q

Why do we use relative mass?

A

This is because value of mass is so small

3
Q

What is a nucleon?

A

Is protons and neutrons put together

4
Q

How do protons in the nucleus stay in the same place when they are same charge (positive & positive)?

A

They do not repel as strong nuclear force act over the small size of the nucleus and bind the nucleons together

5
Q

How can you identify an element?

A

By its’ atomic number and its’ mass number

6
Q

What is the mass number a measure of?

A

An atoms mass compared to other atoms

7
Q

What are stable isotopes?

A

Isotopes that are not radioactive

8
Q

What determines the chemical properties of an element?

A

Depends on the number and arrangement of the electron in its atoms

9
Q

How are isotopes different and similar?

A

The have the same chemical properties

They have slight differences in physical properties, rate of diffusion and nuclear properties

10
Q

What is isotope signature?

A

Elements that occur in space that contain different percentages of isotopes

11
Q

What does relative atomic abundance?

A

Is the percentage of each isotope that naturally occurs on Earth

12
Q

What can mass spectrometer be used for?

A

It can be used to analyse samples in competitive sports for drugs or drug testing in sports

Can be used to identify the mass of an element, an isotope or an molecule - which can be used to identify particles

13
Q

What are the types of spectrometers?

A

Time of Flight Mass Spectrometer

14
Q

What is mass spectrum?

A

Is a chart that is produced by a mass spectrometer

15
Q

Why do scientist use relative atomic mass?

A

As atoms have a very small mass

16
Q

What does relative mean?

A

Means the mass of one atom compared with another

17
Q

What does Relative Atomic Mass mean?

A

It means the average mass if an atom compared with 1/12 the mass of a carbon-12 atom

18
Q

Formula for Relative Atomic Mass?

A

RAM Ar = Average Mass of one atom of an
element
—————————————————————-
1/12 the mass of one carbon 12 atom

19
Q

Formula for Relative Molecular Mass?

A

RMM (Mr) = Average mass of one molecule
———————————————-
1/12 the mass of one carbon-12 atom

20
Q

What does Relative Molecular Mass mean?

A

Is the mass of an molecule compared with 1/12 the mass of a carbon-12 atom

21
Q

What does Relative Isotopic mass?

A

Is the mass of an atom of an isotope of an element on a scale where an atom of Carbon-12 is 12

22
Q

How can Mass spectrometer be used to find Mr values?

A

1) The sample is vaporised and molecules are introduced into the mass spectrometer
2) Sample is bombarded by electrons - can then knock electrons off the molecule. As a result, producing a positively charged ion called molecular ion (M+)
3) Most of these molecular ions split into fragments by bombarding electrons but some remain intact

=> A line is then represented on a mass spectrum - which represents the relative atomic mass of the sample (if an isotope there is more than one molecular ion peak - as they have different masses)

23
Q

What is ionisation energy?

A

The energy required to remove an electron from an atom in its gaseous state

24
Q

What does First Ionisation Energy?

A

The energy required to remove electron

25
Q

What does Second Ionisation Energy?

A

The energy required to remove the second electron from an atom

26
Q

~Not a flashcard

A

Must know half equation for first Ionisation Energy

27
Q

What does successive ionisation energies mean?

A

Is the ionisation energy values for removing the second and subsequent electrons

28
Q

What is Ionisation energies measured in?

A

KJ mol-1

29
Q

Why do we measure Ionisation energies in KJ mol-1?

A

The is because ionisation energies for one atom are so small

30
Q

What is the general trend in first ionisation energy in Group 3? How does it provide evidence of shells and sub-shells?

A

> There is a sharp fall in ionisation energy between neon and sodium and between argon and potassium as electrons enter a new shell
There is an overall increase in first ionisation energy across Period 3 as the positive charge on the nucleus increases and electrons are attracted more strongly.
An increase in ionisation energy for each sub shell as the charge on the nucleus increases and electrons are more strongly attracted
A fall in ionisation energy between magnesium and aluminium as electrons start to fill new sub-shell (3p). Evidence of new sub-shell being filled

31
Q

What is the general trend of First ionisation energies in Group 2 elements?

A

First Ionisation energies decrease as you go down Group 2 - meaning first electron becomes easier to remove

32
Q

Why does the general trend of First ionisation energies in Group 2 elements go down as you go down Group 2?

A

> This is because as the number of electron shells between the outer electron and the nucleus increases., the electrons shield the outer electron from the attraction of the nucleus
The radius of each atom increases as you go down Group 2 - the distances between the outer electron and the nucleus is increasing

{As a result, the outer electrons are easier to remove and the first ionisation decreases….. This provides evidence of electron shells}

33
Q

What does First Ionisation energy measures?

A

Measures how much energy that is needed to remove one mole of electrons from a mole of atom