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AS LEVEL - CHEMISTRY > 1.2 - Basic Ideas About Atoms > Flashcards

1.2 - Basic Ideas About Atoms Flashcards

1
Q

Atomic Number

A

The number of protons in the nucleus of an atom

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2
Q

Mass Number

A

The number of protons and neutrons in the nucleus of an atom

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3
Q

Isotope

A

Atoms having the same number of protons but a different number of neutrons

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4
Q

Ions

A

A particle where the number of electrons does not equal the number of protons. Has an electrical charge due to loss or gain of electrons.

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5
Q

Alpha-particle

A

A helium nucleus (Two protons and two neutrons). Positively charged.

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6
Q

Beta-particle

A

A stream of fast moving, high-energy electrons - negatively charged

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7
Q

Gamma-particle

A

A high energy EM wave

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8
Q

Define Radioactive decay

A

The process of emitting radiation by unstable isotopes when their nucleu divides.

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9
Q

Penetrating power of each radiation

A

MOST -
Gamma - Several cm of lead or M of concrete
Beta - Stopped by mm of aluminium
Alpha - Stopped by paper / air

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10
Q

Effect of an electric field on radiation?

A
  • Gamma rays are unaffected
  • Beta particles are negatively charged and so are deflected toward the positive plate
    -Alpha particles are positively charge and so deflect toward the negative plate.
    -Alpha is LARGER and SLOW MOVING so deflects slower than beta
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11
Q

Alpha Emission effect on element

A

Mass = -4
Atomic No. = -2
4
2 α

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12
Q

Define Electron Capture

A

Also called Inverse Beta
An orbital electron is captured by a proton in the nucleus
This forms a neutron and emits a neutrino

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13
Q

Beta Emission effect on element

A

Mass = 0
Atomic No. = +1
0
-1 β

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14
Q

Electron Capture effect on element

A

Mass = 0
Atomic No. = -1 (Lost a proton)
Electron is on LHS of equation

40 0 40
19 K + -1 e- —-> 18 Ar

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15
Q

Positron Emission effect on element
(β+ decay)

A

Mass = 0
Atomic No. = -1
0
1 β ON RHS

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16
Q

Define Positron Emission
β+ decay

A

A proton is converted into a neutron while releasing a positron

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17
Q

Gamma Emission effect on element

A

No affect on mass or atomic no.
Just and Y symbol on the end of equation

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18
Q

Which is the only emission that affects mass?

A

Alpha - Mass number -4
Because 4 is the mass number of a helium nucleus

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19
Q

Which emission type adds one to the atomic number?

A

Beta Emission

20
Q

Difference between electron capture and positron emission in equations

A

Both -1 on atomic number
Electron capture is on LHS and written with electron symbol
Positron emission uses Beta symbol and is on RHS

0 0
-1 e- 1β

21
Q

Define Half Life

A

The time taken for half the atoms in a radioisotope to decay

22
Q

Health Hazard of radiation

A

Ionisation radiation can damage DNA
This can cause cancerous mutations
Changes in cell function or cell death in high doses

23
Q

What is the most dangerous type of radiation to the body?

A

-Gamma is the most dangerous outside the body - Only one with penetrating power
-Alpha is the most dangerous inside the body - Most ionising

24
Q

Three areas where radiation is used

A

Health & Medicine
Carbon dating
Industry

25
Q

Uses of radiation in Health and medicine

A

Radiotherapy - killing cancer cells (Cobalt-60)
PET Scans - Injecting a radioactive tracer )(Technetium-99)

26
Q

Uses of radiation in Carbon dating

A

Carbon-14 used to calculate the age of plant and animal remains
All organisms absorb carbon. When the organism dies it stops absorbing Carbon-14 and it decays. The C-14 levels can be used to calculate the age of the remains. (When it stopped absorbing CO2)

27
Q

Uses of radiation in Industry

A

Ionising radiation can be used to sterilise equipment
Thickness of metal - Metal is placed between rollers, with the radioactive source and detector on each side - The amount of radiation detected controls if the rollers roll the metal thicker or thinner.

28
Q

How do electrons behave in an orbital?

A

Electrons have opposite spins in an orbital to reduce repulsion.
Drawn as opposite arrows

29
Q

How many electrons in an S-Orbital?

A

2 Max

30
Q

How many electrons in a P-Orbital?

A

6 Max

31
Q

How many electrons in a D-Orbital?

A

10 Max

32
Q

How do electrons fill a subshells? (Hund’s Rule)

A

Each orbital will fill first with one electron before a second is added.
Electrons prefer to be alone.

33
Q

In which order to electron shells fill?

A

1s 2s 2p 3s 3p 4s 3d 4p 5s

34
Q

How can electron configuration be written quicker?

A

For convenience, you can use the previous Noble gas and work from that point on.

35
Q

Exceptions to subshell filling order?

A

Copper and Chromium

36
Q

How does Chromium fill its subshells?

A

Only 1 electron in all on 4s and 3d

37
Q

How does Copper fill its subshells?

A

1 Electron in 4s
And 10 in 3d

38
Q

What is ionisation?

A

The process of removing electrons from an atom.

39
Q

Define First Ionisation Energy?

A

The energy required to remove one mole of electrons from one mole of gaseous atoms, under standard conditions.

40
Q

Equation for Ionising

A

X(g) —-> X+(g) + e-

41
Q

Trends in successive ionisation - Why?

A

-Every time you remove an electron the proton/electron ratio increases, meaning more energy is required to remove an electron
As each electron is removed there is less electron-electron repulsion, so each shell will be drawn slightly closer to the nucleus.
When electrons become closer to the nucleus, the nuclear attraction increases, therefore more energy is needed to remove an electron.

42
Q

Emission Spectra explanation

A

When an atom gains energy, electrons are excited and jump to a higher energy level/ shell further from the nucleus.
When electrons fall back down to a lower energy level quantised radiation is emitted.
The colourful lines occur when electrons fall the n=2, emitting energy which in the form of visible waves.

43
Q

Explain Absorption Spectra

A

-All atoms and molecules absorb lights of certain wavelengths, the black lines occur where wavelengths have been absorbed.
Wavelengths of these lines correspond to energy taken in by atoms to promote electrons.

44
Q

Equations for wavelength?

A

E =hf
C = fλ

45
Q

What is the convergence limit?

A

n = infinity
The point at which the energy of an electron is no longer quantised.
The atom has been ionised

AS LEVEL - CHEMISTRY (6 decks)

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