Atomic Structure

Question 1

What is an orbital?

Answer 1

A region within a subshell of an atom that can hold up to 2 electrons with opposite spins.

Question 2

What is an subshell?

Answer 2

A subdivison of electrons shells seperated by orbitals. These are called s, p,d and f sunshells.

Question 3

How many orbitals are in each sunshell?

Answer 3

s-subshell=1 orbital (2 electrons)
p-subshell= 3 orbitals (6 electrons)
d-subshell= 5 orbitals (10 electrons)
f-subshell= 7 orbitals (14 electrons)

Question 4

Why are the 4s orbitals filled before the 3p orbitals?

Answer 4

The 4s orbitals are at a lower energy level so are filled first

Question 5

What elements do not fill the 4s orbital before the 3p orbital and why?

Answer 5

Chromium and copper as the 4s orbital fills with only 1 electron so that there is a more stable configuration within the 3d orbital.

Question 6

What shaped is the s orbital?

Answer 6

Spherical

Question 7

What shaped is the p orbital?

Answer 7

Dumbbell

Question 8

Define first ionisation energy

Answer 8

The minimum energy require to remove 1 mole of electrons from 1 mole of atoms in a gaseous state.

Question 9

Is ionisation energy exothermic or endothermic?

Answer 9

Endothermic

Question 10

What is the trend in ionisation energy across a period?

Answer 10

Ionisation energy increases across a period as the number of protons increases. Thus atomic radius decreases and a greater electrostatic force of attraction is exerted between the nucleus and the outer electron. More energu is required overcome this force.

Question 11

What is the trend in ionisation energy down a group?

Answer 11

Ionication energy decreases down a groupas the atomic radius and shielding increases so the electrostatic forces of attraction between the nucleus and outer electron decreases making it easier for the outer electron to be removed.

Question 12

How does atomic radius affect ionisation energy?

Answer 12

The distance of the outer electron from the nucleus means that the further away the outer quantum shell, the lower its ionisation energy. The effect of nuclear charge will decrease as the electrons get further away from the nucleus.

Question 13

How does the nuclear charge affect ionisation energy?

Answer 13

As the number of protons increases and size of the positive charge in the nucleus increases. Thus the effecr of the nuclear charge increases and the value of successive ionisation energies increases also.

Question 14

what is electron shielding?

Answer 14

When the inner shells electrons repel the electrons in the outer shells reducing the effect of nuclear charge.

Question 15

How does shielding affect ionisation energy?

Answer 15

The more filled the innner shells between the nucleus and the electron to be removed the greater the shielding and the lower the ionisation energy as effect of nuclear charge is decreasing.

Question 16

What is radioactive decay?

Answer 16

The process that takes place when an unstable nuclei (imbalanced ratio of protons and neutrons) loses energy by emitting radiation inorder to become more stable.

Question 17

What is alpha decay and what are its features?

Answer 17

Decay in which the nuclei loses 2 protons and 2 neutrons, thus reducing the atomic number by 2 and the mass number by 4. It is the equivalent to a helium atom.
*Least penetrating- stopped by thin paper
*Most ionising- carries 2+ charges

Question 18

What is beta decay and what are its features?

Answer 18

Decay in which an electron is released and the decay of a neutron in the nucleus forms a proton or vice versa. Thus reducing the atomin number by 1 but the mass number remains the same.
*more penetrating than alpha radiation- stopped by 5mm thich aluminium
*Less ionising than alpha radiation

Question 19

What is beta+ decay/positron emissom and what are its features?

Answer 19

A beta+ particle is an antiparticle to an elctron meaning it has the same mass but an opposite charge to an electron. (+1 not -1). Thus increases the atomic number by 1 when released but has no effect on the mass number.

Question 20

What is electron capture?

Answer 20

Also known as inverse beta decay when one orbital electron is captured by sa proton in the nucleus forming a neutron and emitting an elctron neutrino. Thus the atomic number is reduced by 1 but the mass number remains the same.

Question 21

What is gamma radiation?

Answer 21

A type of electromagnetic radiation rather than a particle. It has a short wavelenght and high frequency.
*Most penetrating- stopped by thick lead
*Least ionising

Question 22

Compare the range in air of alpha, beta and gamma radiation

Answer 22

Alpha- Less than 5cm
Beta- Less than 1m
Gamma- Infinite range

Question 23

How are alpha particles affected by electric and magnetic fields?

Answer 23

Alpha particles are deflected by a magnetic field confirming that they have a charge. The direction of the deflection demonstrates that they must be positively charged.

Question 24

How are beta particles affected by electric and magnetic fields?

Answer 24

Beta particles are defleted bt a magnetic field in the opposite direction to alpha particles confirming that they have a negative charge.

Question 25

How are gamma particles affected by electric and magnetic fields?

Answer 25

Gamma rays are unaffected byt magnetic fields showing that they have no charge. They do not experience a force when passing through.

Question 26

What are the consequences of radiation on living cells?

Answer 26

When radiation interacts with living cells it may damage and cause mutations to the cells and cause the formation of cancerous cells or lead to cell death at higher doses. *Outside the bpdy gamma is the most hazardous *Inside the bpdy alpha is most dangerous

Question 27

Describe how radiation is used in medicine

Answer 27

•Cobalt-60 in radiotherapy for the treatment of cancer as the high energy gamma radiation can kill cancerous cells. •Technetium as a tracer for diagnostic purposes.

Question 28

Describe how radiation is used in radio dating

Answer 28

•Carbon-14 can be used to calculate the age of organisms •Potassium-40 can be used to estimate the geological age of rocks.

Question 29

Describe how radiation is used in analysis

Answer 29

Dilution analysis means using labelled substances to find the mass of a substance in a mixture. •Measuring the thickmess of metal using beta decay.

Question 30

What is radioactive half life?

Answer 30

The time it takes for the radioactivity ot the number of unstable nuclei present in a sample to halve.

Question 31

Explain electron transitions within spectra

Answer 31

When an electron moves from a higher energy level to a lower energy level, a photon is released to help conserve energy. When it gains energy to move up an energy level, photons are absorbed to provide energy. The specific wavelengths and energies pf photons can be seen as lines on a spectra/.

Question 32

What is an absorption spectra?

Answer 32

When light energy shines through gaseous atoms, photons of certain energies and wavelengths may be absorbed causing an electron to jump up an energy level. The black lines represent the 'missing' frequencies.

Question 33

What is an emission spectra?

Answer 33

When white light is passed through a prism a spectra is formed. When the atomd are given energy, the electrons become excited. When the energy source is removed the electrons emit energy as light. The lines displayed represent frequencies of emitted photons from when an electron has moved down an energy level.

Question 34

What is the hydrogen spectra?

Answer 34

When the hydrogen atoms absorbs energy, its electron jumps up an energy level. When it emits energy in the form of electromagnetic radiation the electron falls back down. This is seen on the spectrum as a line as the energy emitted is equal to the difference between the 2 energy levels. *As the frquencies increase, the lines become closer toegther bauise the energy difference between the shells lessen.

Question 35

What is the equation that links energy to frequency?

Answer 35

Energy(J)= Plancks constant x frequency of photon(HZ) E=hv

Question 36

What is the equation that links wavelength to frequency?

Answer 36

Frequency(Hz)=Speed of light(m/s) / Wavelength(m)

Question 37

What is the convergency limit?

Answer 37

The convergency limit corresponds to a point at which the energy of an elctron is no longer quantised maning th enucleus now has no influence on the electron, so the atom is ionised.