Atomic orbitals and electronic configurations

Question 1

………… first put forward the quantum theory

Answer 1

Max Planck

Question 2

Max Planck was the first to put forward the……………

Answer 2

quantum theory

Question 3

the quantum theory is

Answer 3

used to describe the arrangement of electrons around the nuclei of atoms

Question 4

according to the quantum theory,

Answer 4

electrons can only exist in certain well-defined energy levels called quantum shells

Question 5

a quantum shell

Answer 5

defines the energy level of an electron

Question 6

electrons in the first quantum shell have

Answer 6

the lowest energy for that element

Question 7

the first quantum shell is located in

Answer 7

the region closest to the nucleus

Question 8

each quantum shell, apart from the first, is

Answer 8

divided into subshells of slightly different energy levels

Question 9

there is only one …….. in the first…………labelled………

Answer 9

subshell in the first quantum shell, labelled 1s

Question 10

the second quantum shell has

Answer 10

two subshells labelled 2s and 2p

Question 11

electrons in the 2p subshell have……..than electrons in the 2s subshell

Answer 11

a slightly higher energy level than the electrons in the 2s subshell

Question 12

the third quantum shell is divided into

Answer 12

three subshells, 3s, 3p and 3d.

Question 13

the fourth quantum shell is divided into

Answer 13

four subshells, 4s, 4p, 4d and 4f.

Question 14

each subshell contains

Answer 14

orbitals

Question 15

orbitals are

Answer 15

regions within atoms that can hold up to two electrons with opposite spins

Question 16

the electron in a hydrogen atom is in a ……… so

Answer 16

an s subshell so the orbital is described as a 1s orbital

Question 17

s orbitals are……. in shape

Answer 17

spherical

Question 18

2s orbitals are…………than 1s orbitals

Answer 18

larger

Question 19

to draw orbitals, we use………….axes

Answer 19

x,y and z as 3D Cartesian axes ( axes at mutual right angles)

Question 20

there is a …% probability of finding the electron within the boundaries of its s orbital

Answer 20

90%

Question 21

the 2p subshell contain

Answer 21

three separate p orbitals, Px, Py and Pz

Question 22

the p orbitals are …………in shape

Answer 22

elongated dumbbell

Question 23

p orbitals have variable

Answer 23

charge density

Question 24

there is a …..% probability of finding the electron within the boundaries of its p orbital

Answer 24

90%

Question 25

the only difference between Px, Py and Pz orbitals is

Answer 25

their orientation in space

Question 26

Px, Py and Pz orbitals are arranged at

Answer 26

mutual right angles

Question 27

the first quantum shell can hold

Answer 27

2 electrons

Question 28

the second quantum shell can hold

Answer 28

8 electrons

Question 29

the third quantum shell can hold

Answer 29

18 electrons

Question 30

the fourth quantum shell can hold

Answer 30

32 electrons

Question 31

generally, electrons occupy

Answer 31

the next orbital when the previous one is full

Question 32

for all the elements after calcium,

Answer 32

the energy of 3d orbitals is less than that of 4s orbitals

Question 33

Hund's rule states that

Answer 33

electrons will occupy the orbitals singly before pairing takes place

Question 34

with knowledge that for elements after calcium in the periodic table the 3d orbital has less energy than the 4s orbital, explain why the electronic configuration of scandium (next after Ca) is 3d(1) 4s(2) and not 3d(3).

Answer 34

the 3d orbitals are more compact than 4s ones, so electrons in the 3d orbital have a greater mutual repulsion than they would in the 4s orbital.

Question 35

the Pauli Exclusion Principle states

Answer 35

that two electrons cannot occupy the same orbital unless they have opposite spins. Electrons spin is usually shown by the use of upward and downward arrows