Chapter 3: Electrons in atoms

Question 1

What is the Principle quantum Shells?

Answer 1

they are regions at various distances from the nucleus that may contain up to a certain number of electrons. The first quantum shell contains up to 2 electrons, the second up to eight and the third up to 18.

Question 2

What is the electronic configuration?

Answer 2

It is a way of representing the arrangement of electrons in atoms showing the principle quantum shells, the subshells and the number of electrons present. the electrons may also be shown in boxes.

Question 3

What is ionization energy?

Answer 3

it is the energy needed to remove 1 mole of electrons from1 mole of atoms of an element in the gaseous state to form1 mole of gaseous ions.

Question 4

What is successive ionization energies?

Answer 4

Hi1, Hi2 and so on, it is the energy required to remove the first, then the second and then the thridelectrons and so on from a gaseous atom or ion, producing an ion more positive with one more positive charge each time. it is measured in kJ per mole.

Question 5

What are the two main characteristics of successive ionization energies?

Answer 5

1. It consistently increases because the attarctive forces with the positive charges increases.
2. there are occasional big jumps because the energy level becomes closer to the nucleus so the attractive force becomes stronger.

Question 6

What are the three main factors that influence successive ionization energies?

Answer 6

1. the size of the nuclear charge: Higher proton numbers increase the attractive force.
2. The Distance of outer electrons from the nucleus: the force of attraction decreases as the elctrons gets further and further away.
3. Shielding effect of inner electrons: it is the ability of inner shell eelctrons to reduce the effective charge on electrons in the outer shell by exerting a repulsion.

Question 7

describe the successive ionization energies of sodium (11 protons).

Answer 7

1. taking out the outer shell electron is rather easy due to high shielding and large distance.
2. the 8 electrons in the second shell progressively get harder to remove due to increasing attractive forces.
3. the last two are ver hard to remove due to neglible shielding, small distance and high positive charge.

Question 8

What is th purpose of interpreting successive ionization energies?

Answer 8

1. To confirm the electronic configuration

2. To confirm the umber of outer shell electrons.

Question 9

What are subshells of and atom?

Answer 9

they are regions in the principle quantum shells thathave different energy levels depending on their distance from the nucleus.

Question 10

what are the maximum numers of electrons that can be in each subshell?

Answer 10

s = 2
p = 6
d = 10

Question 11

What are atomic orbitals?

Answer 11

they are regions of space outside the nucleus that’s can be occupied by one or, at most, two electrons. They have different shapes.

Question 12

explain how the shells and orbitals of electrons are filled.

Answer 12

they are filled by the electron with the lowest energy. this is in order for the lectron to be as stable as possible.

Question 13

explain how an electronic configuration is represented.

Answer 13

the principle quantum shell is a big number.
the subshell is represented by either an s,p,d or f. and finally, the number of electrons is represented by an uppercase number.

Question 14

explain the relationship between the periodic table and orbitals.

Answer 14

groups 1 and 2 go into an s block alongside He and H.
Groups 3 - 8 go into a p block.
and finally, the transition elements go into a d block.

Question 15

why do electrns spin in opposite directions?

Answer 15

to reduce the repulsion effect.

Question 16

Explain the trend of te ionization energies across a period.

Answer 16

1. there is a large increase between hydrogen and helium due o the increased no. of electrons.
2. there is a rapid decrease to the next periods the thedistance increase and the new electron is isolated.
3. there is a stepped increase to the end of a period as the new electrons make it harder to be removed, and all other factors stay the same.
4. there maybe slight decreases due to the increased distance and shielding between orbitals.
5. within the same orbital there is an additional repulson force given in paired orbitals , reducing the ionization energy.

Question 17

what does spin-pair repulsion mean?

Answer 17

it is when electrons repel each other as they have the same charge. Electrons arrange themselves so that they first singly occupy different orbitals in the same sublevel. After that, they pair up with their spins opposed to each other.

Question 18

what is the pattern down a group?

Answer 18

the first ionization energies decrease. this is due to the increased distance between the nucleus and the orbitals, the increased shielding of the nucleus by the new shells and these outweigh the increased nuclear charge.