Gen Chem.

Question 1

Atomic Number
Mass Number
Number of protons
Are electron included in the mass calculations?

Answer 1

1. Atomic number (Z): number of protons
2. Mass number (A): number of protons + number of neutrons
3. Number of protons = Number of electron in a neutral atoms.
4. Electron aren’t included in the mass calculations because they are much smaller.

Question 2

What are isotopes?
Atomic mass and Mass number?
How do we give names to isotopes?
which ones are named differently?

Answer 2

Atoms of the same element have the same atomic number (Z), but not necessarily the same Mass number (A).

Because the Atomic Mass of an atom (in amu) is nearly equal to the mass number (A), it also changes according to isotopes.

Isotopes differ in number of neutrons and are referred to by the name of of the element (carbon-) followed by the mass number (13), so Carbon-13

Only three isotopes of Hydrogen are given unique names:

1. Protium: one proton and an atomic mass of 1 amu
2. Deuterium: 1 proton, one neutron and an atomic mass of 2 amu
3. Tritium: 1 proton, 2 neutrons and an atomic mass of 3 amu.

Question 3

Mole

Avogadro’s number

Answer 3

A mole is a number of things.

Avogadro’s number: 6.02 x 10^23

Question 4

Atomic mass vs. atomic weight

Answer 4

1. Atomic mass is nearly synonymous with mass number (A).
2. Atomic weight is a weightier average of natural occurring Isotopes of that element (number reported on the periodic table)

Question 5

Half-Lives

Answer 5

Half-Lives is a marker of stability ; generally longer-lasting isotopes are more abundant.

Helps determine the relative proportions of these isotopes.

Question 6

Max Planck

Answer 6

Max Planck developed the first quantum theory. Proposing that energy emitted as electromagnetic radiation from matter comes in discrete bundles called Quanta.

Energy of a Quantum is determined by :
E=hf
E= Quantized energy
h= Planck's constant 6.626 x 10^-34 J*s
f (v)= frequency of the radiation.