atomic_structure_review_

Atomic Structure

Overview of atomic structure.

Components of an Atom

• Nucleus: Very dense, small nucleus (contains most of the atom's mass).

• Electron Cloud: Surrounds the nucleus; mass of electrons is negligible.

• Electrostatic Attraction: Between negative electrons and positive nucleus, keeping the atom together.

Element Notation

• Mass Number (A): Represents total count of protons and neutrons.Formula: A = Z + N (Z = atomic number, N = neutron number).

• Atomic Number (Z): Number of protons in the nucleus, which also indicates number of electrons in a neutral atom.

• Chemical Symbol (X): Representational symbol for the element.

Relationships in Atomic Structure

• Mass Number (A): Sum of protons and neutrons.

• Atomic Number (Z): Number of protons and electrons in a neutral atom; smaller of the two numbers between protons and neutrons.

Isotopes

• Definition: Atoms with the same number of protons but different numbers of neutrons, resulting in different mass numbers.

• Chemical Properties: Remain unchanged among isotopes.

• Notation: Examples include C-12, C-13, C-14 (number represents the mass number).

Isotope Examples

• Hydrogen Isotopes:

  • Hydrogen-1: Mass number 1.

  • Hydrogen-2 (Deuterium): Mass number 2.

  • Hydrogen-3 (Tritium): Mass number 3.

Well-Known Isotopes Table

• Hydrogen (H): 1 proton, 0 neutrons, 1 electron.

• Deuterium (H): 1 proton, 1 neutron, 1 electron.

• Tritium (31H): 2 protons, 1 neutron, 1 electron.

• Carbon-12 (12C): 6 protons, 6 neutrons, 6 electrons.

• Carbon-13 (13C): 6 protons, 7 neutrons, 6 electrons.

• Carbon-14 (14C): 6 protons, 8 neutrons, 6 electrons.

• Oxygen isotopes and their respective compositions.

• Uranium isotopes: U-235 and U-238 details.

Isotope Calculations

• Relative Atomic Mass Calculation Formula:Ar = (%A x Ar(A) + %B x Ar(B) + ...) / 100

• Example Question: Calculate relative atomic mass of Chlorine using isotopes Cl-35 and Cl-37 with given abundances.

Example Calculation Problems

• Calculate the average atomic mass of magnesium (Mg) given three natural isotopes and their abundances: 24Mg, 25Mg, 26Mg.

• Determine the relative atomic mass of silicon (Si) from the given isotopic abundances.

% Abundance Calculations for Isotopes

• Nitrogen Isotopes Calculation:N-14 and N-15 isotopes with given average atomic mass of 14.007.Let % of N-14 be x; % of N-15 will be (1-x).Calculation shows N-14 is 99.3% abundant, and N-15 is 0.7% abundant.

Isotope Abundance for Copper

• Copper Isotopes: Exists as Cu-63 and Cu-65. Given average atomic mass of Cu = 63.55.Results: Cu-63 = 72.5%, Cu-65 = 27.5% abundance.

Lithium Isotope Abundance

• Lithium Isotope Information: Elemental atomic mass of lithium is 6.941 with isotopes 6Li and 7Li.Given masses: 6.0151 and 7.0160.Results show %Li-6 = 7.49%, %Li-7 = 92.51%.