Lecture 1

Question 1

Arrangement of elements in the periodic table is based on ……

Answer 1

Reactivity which is determined by valence electrons

Question 2

What is the atomic number?

Answer 2

Number of protons in the nucleus- in neutral atoms is same as number of electrons.

Question 3

What is the mass number

Answer 3

Number of protons and neutrons (nucleons) in the nucleus

Question 4

What property is determined by mass number?

Answer 4

Physical properties

Question 5

What property is determined by electrons?

Answer 5

Chemical reactivity

Question 6

Why is mass number not a whole number?

Answer 6

Elements vary in number of neutrons (isotopes) abundance is calculated

Question 7

Define isotope

Answer 7

Atoms with same number of protons different number of neutrons

Question 8

What are the 3 isotopes of H?

Answer 8

Protium H
Deuterium 2H
Tritium 3H

Question 9

Which isomer of hydrogen is reactive?

Answer 9

Tritium

Question 10

Define Radioisotope

Answer 10

Radioactive isotope it breaks down

Question 11

Why do radioisotopes breakdown

Answer 11

Due to unstable nuclei
Unstable ratio of protons: neutrons

Question 12

Define Half Life

Answer 12

Time taken for activity of a radioactive substance to 1/2 as a result of radioactive decay

Question 13

What is it meant by “half life of tritium is 12.32yrs”?

Answer 13

Half of tritium will degrade in 12.32 yrs

Question 14

How to calculate molecular mass

Answer 14

Sum of atomic masses in a molecule

Question 15

Why is CDCL3 used as NMR solvent and not CHCl3?

Question 16

What is the difference of C14 with the other isotopes?

Answer 16

-Radioactive form (unstable nuclei)
- trace amounts

Question 17

Uses of C14

Answer 17

Carbon dating

Question 18

Explain carbon dating
Why is c14 suitable?

Question 19

What does degenerate mean?

Answer 19

Orbitals have same energy level

Question 20

Rules for writing electronic configurations

Answer 20

• Max 2e in each orbital
• e have opposite spins
• e fill empty degenerate orbitals before start pairing

Question 21

Why e don’t repel each other in orbitals?

Answer 21

e have opposite spins so produce opposite magnetic fields so e attract each other

Question 22

What does the lewis symbol represent?

Answer 22

Represents valence electrons as dots

Question 23

Valence electron means

Answer 23

Electrons in the outermost shell

Question 24

Can group number be used to calculate valency

Answer 24

Group number= valency number

Question 25

What does the Octet rule state?

Answer 25

Atoms gain/ lose e to obtain noble gas electronic configuration( usually 8e)
So they get a stable full shell

Question 26

Why are noble gases unreactive?

Answer 26

Have full, stable electronic shell- octet rule met

Question 27

Medical uses of Xenon

Question 28

What is ionic bonding?
Which type of atoms form ionic bond?
Property of ionically bonded structures

Answer 28

Electrostatic force of attraction b/w cation and anion creat solid crystal structures with high mp and bp

Question 29

What is covalent bonding?
Which type of atoms form covalent compounds?
Structure of covalent compounds

Answer 29

Sharing pair of e b/w 2 non metals
Molecules with low mp and bp are produced