Atomic Structure

Question 1

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What is Atomic Structure?

Answer 1

Refers to the arrangement of subatomic particles (protons, neutrons, and electrons) within an atom.

Question 2

What is Daltons Atomic Theory (i)?

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Answer 2

Each particle is made up of tiny particles called atoms

Question 3

What is Daltons Atomic Theory (ii)?

Answer 3

Atoms of a given element are identical but the atoms of on element are different from the atom of other element

Question 4

What is Daltons Atomic Theory (iii)?

Answer 4

Atoms of one element can not be changed into a different element by chemical reaction

Question 5

What is Daltons Atomic Theory (iv)?

Answer 5

Atoms are neither created or destroyed in a chemical reaction

Question 6

What is Daltons Atomic Theory (v)?

Answer 6

Compounds are formed when one atom of more than one element combine
- a given compound always has the same relative number and kind of atom

Question 7

What are the limitations of Dalton’s Atomic Theory (i)

Answer 7

Dalton’s theory states that atoms are indivisible however this does not account for the subatomic particles e.g. proton, electron, neutron.

Question 8

Limitations of Dalton’s Atomic Theory (ii)

Answer 8

Dalton’s theory states that atoms of the same element have identical mass and density however this does not account for isotopes

Question 9

What are the limitations of Dalton’s Atomic Theory (iii)

Answer 9

Dalton’s theory states that the mass of the different elements must differ, so it doesn’t account for isobars (when two different elements share the same mass number)

Question 10

What are the limitations of Dalton’s Atomic Theory (iv)

Answer 10

Elements need not combine in simple whole number ratios to form compounds e.g. organic compounds do not feature simple ratio of consistent atom

Question 11

What are limitations of Dalton’s Atomic Theory (v)

Answer 11

This theory does not account for the allotrope e.g. the difference in the property of diamond and graphite both of which contain only carbon atoms

Question 12

Who discovered the electron?

Answer 12

J.J Thompson (1832 -1919)

Question 13

Cathode Ray Tube Experiments (1897

Know the experiment

Answer 13

In a cathode ray tube (a vacuum tube with electrodes at each end), Thomson observed a stream of negatively charged particles (later identified as electrons) being emitted from the cathode (the negative electrode) and traveling toward the anode (the positive electrode).

Question 14

Note about the cathode ray experiments

Answer 14

When the magnetic field is on and the electric field is off, the cathode ray strikes point A, when only the electric field is on, the cathode ray strikes point C, when both fields are on or off, they cancel each other out and the ray hits point B

Question 15

Key Observations of the Electron

Answer 15

-Particles could be deflected by both electric and magnetic fields, indicating that they had a negative charge.
-Nature of the Particles: They were much smaller than atoms and carried a negative charge.
-Charge-to-Mass Ratio: Electrons are lighter than hydrogen atoms, the lightest known atom at the time.

Question 16

Charge to mass ratio of an electron

Answer 16

e/m = 1.76*10^2

Question 17

Who discovered the proton?

Answer 17

Goldestein

Question 18

Who discovered the nuclear atom?

Answer 18

Rutherford (1910)

Question 19

Who discovered the Neutron?

Answer 19

James Chadwick(1932)

Question 20

Plank’s Theory

Answer 20

When objects are heated, they emit electromagnetic radiation a piece of iron appears gray at room temp but glows red when heated

Question 21

Plank’s Conclusion

Question 22

A Quanta

Answer 22

The smallest quantity of energy that can be emitted or absorbed in the form of electromagnetic radiation

Question 23

The mathematical relationship between the energy of a quantum and the frequency of emitted radiation

Answer 23

E = hν
E = energy
h = Plank’s constant (6.63*10^-34)
v = frequency of radiation

Question 24

The Photon

Answer 24

The quantum of the electromagnetic field, carrying energy and momentum but having zero rest mass.
𝐸 = ℎ𝜈

Question 25

The Photoelectric Effect

Answer 25

The phenomenon where light striking a metal surface ejects electrons from the metal.

Question 26

Threshold Frequency

Answer 26

The minimum frequency that certain metals must have when exposed to light, for them to emit electrons

Question 27

What is the relationship between # of electrons emitted and intensity of light

Answer 27

The number of electrons emitted is proportionate to the intensity of the light

Question 28

NOTE

Answer 28

An increase in the intensity of the incident light does not increase the energy of the photon electron

Question 29

NOTE

Answer 29

For light with frequency lower than the threshold frequency, no electrons are emitted regardless of the intensity of light

Question 30

NOTE

Answer 30

For light with a frequency greater than the threshold, the number of electrons emitted increase with frequency of light

Question 30

Know how to find the total energy of and electron on the nth level (Eₙ)

Answer 30

(Eₙ) = -Rhc n² ## Footnote R = Ryberg Constant) h = Plank's Constant c = Speed of Light n = principle quatum number

Question 31

NOTE

Answer 31

For light with frequency higher than the threshold frequency, the kinetic energy of the emitted electron increases linearly with frequency of light

Question 32

What is Bohr Model Postulate 1 ## Footnote Prposed by Neils Bohr

Answer 32

-Electrons move in specific permitted circular orbitals and in no other order around the central nucleus

Question 33

What is Bohr Model Postulate 2

Answer 33

Electrons do not radiate energy when in their orbits and have a definite amount of energy in each orbit

Question 34

What is Bohr Model Postulate 3

Answer 34

Under certain conditions, transitions between these stationary states do occur and the transitions are combined by the emission or absorption of radiation

Question 35

Mathematical formula for total energy of an electron in the nth level (Eₙ)

Answer 35

Eₙ = (-Rhc\n²)

Question 36

What is the mathematical formula for an electron moving from one energy level to another

Answer 36

ΔE = (-Rhc/n²₁) + (-Rhc/n²₂) ## Footnote n₁ is final quatum level n₂ is initial quatum level

Question 37

What is the formula that relates wavelength and Rydberg equation

Answer 37

1/λ =R(1/n²₂ - 1/n²₁) ## Footnote n₁ is final quatum level n₂ is initial quatum level

Question 38

What is the uncertainty principle?

Answer 38

The principle that states that due to the dual nature of matter, there is a limit on how precisely we can know simultaneously the location and momentum of an electron ## Footnote Proposed by by Wierner Heinsberg

Question 39

Subshell Quantum Number (l)

Answer 39

Divides the shells into smaller groups of orbitals called subshells l = n - 1

Question 40

Magnetic Quantum Number (m)

Answer 40

Divides the subshells into individual orbitals. It determines the direction of space of the electron cloud surrounding the orbital

Question 41

Degeneracy of Orbitals

Answer 41

Orbitals with the same energy are called degenerate orbital -The total number of different states of the same energy is called degeneracy

Question 42

Examples of Degeneracy of Orbitals

Answer 42

The degree of p orbitals in 3 while the degree of degeneracy of d orbitals is 5

Question 43

Shapes of Orbitals

Answer 43

just look at your notes bro

Question 44

Pauli Exclusion Principle

Answer 44

This states that no two electrons in any one atom may be described by the same set of quantum number -By this we mean that no two electrons in an atom behave in identical manner

Question 45

Hund's Rule

Answer 45

This states that electrons are distributed among the orbitals of the same subshell singly before paring occurs

Question 46

Aufbau Principle

Answer 46

In the building up of atom, elements are fed into the atomic orbital with the lowest energy level first, and each orbital may hold up to two electrons.