Lecture 3 Atoms

Question 1

Define Atoms

Answer 1

The smallest particle of a chemical element that can exist.

Question 2

What was dalton’s atomic theory (1808)?

Answer 2

Theory based on evidence following a hypothesis.
1. Elements are made of atoms
2. Atoms of a element are identical
3. Atoms of one element is different from another
4. Atoms from one element combine with another forms compounds. This compound always has the same no. & types of atoms.
5. Atoms are invisible in chemical processes. Not created or destroyed in chemical reactions but only change the atoms grouping.

Question 3

Define Isotopes

Answer 3

Same atomic no. but different mass.
- different no. of neutrons

Question 4

Define Atomic weight

Answer 4

Weighted avg. of the masses (in AMU) of a particular element isotopes.

Question 5

What is AMU?

Answer 5

• It stands for atomic mass unit.
• equal to 1/12 of the mass of an atom of carbon-12.