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CH1033-134 > MARY - Topic 1 > Flashcards

MARY - Topic 1 Flashcards

1
Q

What is an atom?

A

The smallest unit quantity of an element, that may exist either alone or in chemical combination with another element.

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2
Q

What is the charge and mass on a proton?

A 
Charge = +1.60 x 10^-19 C
Mass = 1.673 x 10^-27 kg
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3
Q

What is the charge and mass on a neutron?

A 
Charge = 0
Mass = 1.675 x 10^-27 kg
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4
Q

What is the charge and mass on an electron?

A 
Charge = - 1.602 x 10^-19 C
Mass = 9.109 x 10^-31 kg
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5
Q

What is the atomic number?

A

No. of P’s or E-‘s

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6
Q

What is the mass number?

A

The no. of P’s and N’s.

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7
Q

What are isotopes?

A

Forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei.

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8
Q

What does 1 atomic mass unit equal (u)?

A

1 Dalton (Da)

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9
Q

What is the value for 1 Da?

A

1.66 x 10^-27 kg

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10
Q

What is Avogadro’s constant?

A

6.022 x 10^23 mol-1

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11
Q

What is the Ar (relative atomic mass)?

A

It’s dimensionless, and defined as the ratio of the average mass of atoms of an element in a sample, to one atomic mass unit (u).

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12
Q

How do we calculate Ar values?

A

Take a weighted mean of the mass no.s of each isotope, they are not generally whole integers.

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13
Q

What is our evidence for isotopes?

A

Mass Spectrometry

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14
Q

How do we organise the PTE?

A

Increasing atomic number.

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15
Q

What did Dalton discover?

A

1800’s

Elements react in the same mass ratios to form a given element. Atoms are tiny, indivisible sold spheres, which make up different elements.

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16
Q

What did Thomson discover?

A

1897

He discovered the electron, which was the first suggestion of sub-atomic particles, and formed the plum-pudding model.

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17
Q

What did Millikan discover?

A

1910

The charge on the electron.

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18
Q

What did Rutherford discover?

A

1909-11

He did a gold-foil experiment which led to the discovery of the nucleus, and showed that atoms were mostly composed of empty space, disproving the plum-pudding model.

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19
Q

When did Rutherford propose the planetary model of the atom?

A

1911

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20
Q

What was the planetary model of the atom?

A

Treats atom as having a small positively charged nucleus, with electrons moving about in large empty volume.

Discovery of the nucleus meant that there had to be a charged particle in it, to balance the charge on the electron. This charged nuclear particle was designated as a proton.

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21
Q

What did Chadwick discover?

A

1932

The Neutron.

22
Q

What was the Gold-Foil experiment?

A

Directed high energy alpha particles at a very thin gold foil. Most a-particles pass through and are undeflected, however a small proportion are deflected back.

23
Q

How many electrons were deflected?

A

1:20,0000

24
Q

What did the gold-foil experiment show?

A

The nucleus was a small dense area of +ve charge, which is surrounded b a large volume of mainly empty space containing electrons.

25
Q

How do we record an emission spectrum of Hydrogen?

A

Pass an electric discharge through hydrogen gas, which splits the molecules in atoms and within the atoms, electrons become excited. When these electrons return to their ground state, they emit energy.

26
Q

What is a spectrum?

A

The result of a spectroscopic experiment.

27
Q

What is spectroscopy?

A

The study of how atoms absorb/emit electromagnetic radiation.

28
Q

What is the frequency?

A

No. of wavelength crests passing a fixed point per second. (Hz) = s-1

29
Q

What is the symbol for frequency?

A

v

30
Q

What is the unit for velocity?

A

c

31
Q

What does c equal?

A

2.998 x 10^8 ms-1

32
Q

What does velocity equal?

A 
velocity = wavelength x frequency
c = λ x v
33
Q

What does 1kHz equal?

A

1kHz = 1000Hz = 1000sec-1

34
Q

What does 1mHz equal?

A

1mHz = 1,000,000Hz

35
Q

What’s the conversion between 1Å and m?

A

1Å = 1 x 10^-10 m

36
Q

What’s the conversion between nm and m?

A

1nm = 1 x 10^-9 m

37
Q

What’s the conversion between pm and m?

A

1pm = 1 x 10^-12 m

38
Q

What’s the conversion between cm and m?

A

1cm = 1 x 10^-2 m

39
Q

What does the visible region of the EM spectrum range from?

A

740nm to 390nm.

40
Q

What did Planck propose in 1900?

A

EM radiation could only be absorbed or emitted in quanta, which are discrete packets with energy stored in them. These quanta could be either absorbed or released, and quanta = photons.

41
Q

How do we calculate the energy of a photon?

A 
E = h x v 
E = h x c/λ
42
Q

What does it mean if E is large?

A

As h is a constant value, frequency must be large if E is large.

43
Q

What does high energy mean?

A

High frequency and short radiation wavelength.

44
Q

What did Einstein suggest?

A

1905

Light energy was made up of photons, and he used this to explain the photoelectric effect (the way that certain metals release electrons when UV light falls on them).

45
Q

What is the photoelectric effect?

A

When UV light falls on a metal, e-‘s are only ejected if Euv > threshold frequency. If it is smaller then no electrons are emitted.

This can only be explained if we consider light as being composed of photons, and each photon must have enough energy to remove an electron from the metal surface, so reach the threshold energy.

46
Q

What happens if Euv is greater than the threshold energy?

A

The excess energy is converted to KE in the ejected electron.

47
Q

What is the work function?

A

The name given to the threshold energy of an electorn in a single atom.

E(total) = hv = work function + E(KE)

48
Q

How do we calculate the work function?

A

Work Function = hv - E(KE)

49
Q

What are the units for the work function?

A

J

50
Q

What does the photoelectric effect demonstrate?

A

Light can behave like a particle.

51
Q

What is the wave nature of light?

A

In the early 1900’s Young did an experiment which involved passing light through two closely spaced slits. The pattern on the screen behind the slits had areas of light and dark. This is because waves can interact constructively (when wave crests coincide) and destructively (when wave crests cancel out). This shows wave-particle duality exists.

CH1033-134 (8 decks)

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