Atomic Structure Flashcards by Andrew James

What is the absolute charge of an electron?

Electron: -1.602 × 10^-19 C or -4.8 × 10^-10 esu

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What is the absolute charge of a proton?

Proton: +1.602 × 10^-19 C or +4.8 × 10^-10 esu

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What is the absolute charge of a neutron?

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What is the absolute mass of an electron?

9.1 × 10^-31 kg

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What is the absolute mass of a proton?

1.672 × 10^-27 kg

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What is the absolute mass of a neutron?

1.675 × 10^-27 kg

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What is the specific charge of an electron?

1.76 × 10^11 C/kg

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What is the specific charge of a proton?

9.58×10^7 C/kg

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What is the specific charge of a neutron?

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Name the elements that have atomic numbers from 21 to 30

Science(Sc)
Teacher(Ti)
Very(V)
Crazy(Cr)
Man(Mn)
Feed(Fe)
Cow(Co)
Nickel
Copper
Zinc

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In Rutherford’s Alpha Ray Scattering Experiment what was the box containing the radioactive element made of? Why?

The box was made of Lead.

Lead is a good absorber of alpha rays, preventing their scattering into the surroundings.

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In Rutherford’s Alpha Ray Scattering Experiment, which radioactive element was used? Why?

Radium was used.

Radium produces a relatively large amount of alpha radiations.

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Name the 4 layers of Rutherford’s Alpha Ray Scattering Experiment

The Lead Box
The Lead Slit
The Gold Foil
The Screen containing ZnS coating

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In Rutherford’s Alpha Ray Scattering Experiment, which element made the foil? Why? Give its atomic number.

Gold(Z - 79) was used since it is highly malleable - it was beaten into a sheet 0.00004 cm thick.

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Observations of the Gold Foil Experiment

Most Rays passed undeviated
Few rays got deflected slightly
Around 1 in 20,000 rays would retrace its path.
Increasing the Z of the target element would increase deflection of the alpha particle as the number of protons would increase.

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What is the radius of the nucleus of an atom? What is the radius of an atom? What is their relation?

Radius of the nucleus = 10^-13
Radius of the atom = 10^-8

Radius of the atom = 10^5 Radius of the nucleus

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Compare the volume of the atom and its nucleus

Volume of a sphere is (4πr³)/3

So Volume of atom : Volume of nucleus = (R/r)³ = (10⁵)³ = 10¹⁵

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Relationship between radius of nucleus and mass number

Radius of nucleus = R₀ × A⅓

R₀ = 1.33 × 10^-13 cm

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What is the formula for force of attraction between 2 charges? Which law does it follow?

According to Coulomb’s Law:

F = K . q₁ q₂/ r²

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Based on Coulomb’s Law what is the formula for PE?

PE = F × d
= K . q₁ q₂/ r² × r
= K . q₁ q₂/ r

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As distance between charges increases, how does PE get affected?

Like Charges:
Greater the separation, lesser the PE

Unlike Charges:
Greater the separation, greater the PE

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What is the formula for distance of closest approach of Alpha particle

PEᵢ + KEᵢ = PEբ + KEբ

at initial position, r = infinity, so PEᵢ = 0
at final position, v = 0, so KEբ = 0

therefore KEᵢ = PEբ

therefore rₘᵢₙ = K . q₁ q₂/ KEᵢ

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What is the ratio of specific charge of proton to specific charge of Alpha particle?

specific charge = charge/mass

therefore proton : alpha particle
1/1 ÷ 2/4 = 2:1

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Define a wave

A method of transport of energy without transfer of matter

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Define amplitude

Height of a crest or depth of a trough

Define wavelength

Distance between two consecutive crests or troughs

Define frequency

Number of waves passing through a point in one second

Define time period

Time taken for one wave to cross a given point

Define speed of a wave

Distance traveled by a wave per unit time

Define wave number

Number of waves in a unit distance

Basic Formula for speed of a wave

c = f * λ

Postulates of Maxwell's Theory

- Theory suggests wave nature - When a charged particle moves, it creates a magnetic component and an electric component - Electric component and magnetic component of the wave are perpendicular to each other and to the direction of propagation of the wave. Such waves are known as electromagnetic radiations

Name the Radiations in the Electromagnetic Spectrum in increasing order of Wavelength

- cosmic rays - gamma rays - x rays - ultraviolet rays - visible spectrum - violet - indigo - blue - green - yellow - orange - red - infrared rays - microwave rays - radiowave rays

What is the speed of electromagnetic radiations?

3 * 10^8 m/s

In what Medium do electromagnetic radiations propagate?

Do not require medium for propagation

Formula for Time Period of a wave

T = 1/v(frequency)

Formula for wave number

wave number = 1/λ(wavelength)

Formula for speed of wave(using wave number)

speed = (f)frequency/(v)wave number

Wave nature can explain

- Interference | - Diffraction

Wave nature cannot explain

- Black Body Radiation | - Photoelectric Effect

Postulates of Planck's Quantum Theory

- Theory suggests particle nature for EMR - According to the theory, thermally hot objects absorb or emit energy - Energy is emitted or absorbed in the form of small packets or bundles known as quantum

Formula for Energy associated with each quantum

E = hf | where h is Planck's constant and f is frequency of the quantum

Value of Planck's constant

6.626 x 10^-34 J.s or 6.626 x 10^-27 erg.s

Formula for Energy of quantum in joules

E = hc/λ(in metres)

Energy of quantum in eV

1240/λ in nm

1 eV in Joules and erg

1. 6 x 10^-19 J | 1. 6 x 10^-12 erg

Centripetal Force of an Electron

F = K[q1 x q2]/r^2 = K[Ze^2]/r^2

Centrifugal Force of Electron

mv^2/r

Formula for velocity of Electron from centripetal-centrifugal force

v^2 = K[Ze^2]/mr

From Bohr's Model, Angular Momentum

mvr = nh/2π

Velocity of an Electron from Bohr's Model

v = 2π*Z*e²*K/n*h

Formula for Radius of an Electron

r = n^2*h^2/4π^2*Z*e^2*m*K

Numeric Formula for Radius of an Electron

r = 0.529 * n^2/Z angstrom

Proportionality for Radius of an Electron

r is directly proportional to n^2/Z

What is Photoelectric Effect?

When light(a photon) of a suitable frequency strikes a metal, it ejects an electron(known as photoelectron)

What is the threshold frequency of a photon?

The minimum frequency of a photon that allows for the emission of a photoelectron when it strikes a metal plate

Photoelectric Effect is exhibited by which elements?

Alkali Metals like Rb, Cs, K

How does voltage of the battery affect movement of photoelectron?

Higher the voltage if the battery, greater the chances of the photoelectron striking the anode

Formula for energy of a photon

Ephoton = hv

Formula for Threshold Energy of a photon

E = hvmin

If frequency of photon is less than threshold frequency

Photoelectron not emitted

If frequency of photon is equal to threshold frequency

Photoelectron emitted

If frequency of photon is more than threshold frequency

Photoelectron emitted with KE

Formula for energy of photon(in terms of charge and voltage)

Energy = Charge * Voltage

Formula for Charge of a photon

Charge = Current * Time

Formula for Energy of a Photon

E = Emin + KEphotoelectron

Threshold Energy for Li

2.4

Threshold Energy for Na

2.3

Threshold Energy for K

2.2

Threshold Energy for Mg

3.7

Threshold Energy for Cu

4.8

Threshold Energy for Pt

6.3

Formula for Intensity of Light

I = E/A*t

If intensity of light increases, what increases(from the formula)

Frequency of the photon remains constant | So only the number of photons can increase when intensity increases

The number of photoelectrons emitted is the same as

The number of photons incident

As intensity of light increases, photocurrent

Increases

Formula for stopping potential

V = KE/q

Numeric Formula for velocity of an electron in orbit

2.18 * 10⁶ * z/n metres per second

Atomic Structure Flashcards

(78 cards)