Atomic Structure

AS

Define atom.

Define atom.

Smallest particle of every state of matter is called atom

Mass and charge of a proton?

Relative Mass: 1 amu

Actual Mass: 1.673 x 10^-27 kg

Charge: + 1.6 x 10^-19 C

Mass and charge of neutron?

Relative Mass: 1 amu

Actual Mass: 1.675 x 10^-27 kg

Charge: zero

Mass and charge electron?

Relative Mass: 1/1840 OR 1/1836

Actual Mass: 9.11 x 10^-31

Actual Charge: -1.6x 10^-19

Behaviour of subatomic particles in an electric field:

• protons are +ve charged so attracted to -ve plate (less deflected, due to its larger mass)

• neutron has no charge so unaffected

• electron -ve charged so attracted to +ve plate

Behaviour of subatomic particles in a magnetic field:

Sequence of general electronic configuration:

1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6, 5s2, 4d10, 5p6…

Define first ionization energy:

Energy required to remove 1 mole of of electron from a gaseous atom to form +1 charged gaseous ion at standard conditions.

Define enthalpy change of atomization:

Energy required to form 1 mol of gaseous atom of any element from its standard state, at standard condition.

Define second ionization energy:

Energy required to remove 1 mole of of electron from a gaseous atom to form +1 charged gaseous ion to form +2 charged gaseous ion at standard conditions.

Factors affecting Ionization Energy.

1. Atomic radii/distance from nucleus/number of shells: Increase in the number of shells makes the valence electron less firmly held in the valence shell so less IE means less energy is required to remove the electron.

Why is the first ionization energy of phosphorus greater than the first ionization energy of silicon.

A phosphorus atom has one more proton than in its nucleus

Which factor helps to explain why the first ionization energies of the Group I elements decrease from lithium to sodium to potassium to rubidium.

The shielding effect of the inner shells increase.

What factor affects value of activation energy?

1. nature of reactants

2. presence of a catalyst

NOTE: Activation energy does not depend upon the temperature, pressure, volume, concentration, or coefficients of reactant.

Why is the first ionisation energy of oxygen less than that of nitrogen?

the oxygen atom has a pair of electrons in one p orbital that repel each other.

Which statement about the electrons in a ground state carbon is correct?

A. Electrons are present in four different energy levels.

B. There are more electrons in p orbitals than there are in s orbitals.

C. The occupied orbital of highest energy is spherical.

D. The occupied orbital of lowest energy is spherical.

Option D. The occupied orbital of lowest energy is spherical.