Atomic structure and electronic configuration

Atomic Structure & Electron Configuration

  • Overview: Atomic structure refers to the organization of protons, neutrons, and electrons in an atom. Electron configuration is the arrangement of electrons in an atom's electron shells.

Electronic Configuration

  • Definition: A shorthand method to describe the electron arrangement within shells (also known as energy levels) of an atom.

  • Also Known As: Electronic structure.

Bohr's Atomic Theory

  • Electrons in Orbit: Electrons revolve around the nucleus in specific paths called shells or energy levels.

  • Energy Levels:

    • Increase in energy as the distance from the nucleus increases.

    • 1st shell (K) can hold 2 electrons, 2nd shell (L) can hold 8 electrons, 3rd shell (M) can hold 18 electrons, and the 4th shell (N) can hold 32 electrons.

  • Filling Order: Shells fill from lowest to highest energy, starting with the closest to the nucleus.

Flame Test Colors

  • Flame Test: Different elements show distinct flame colors when heated due to electron transitions between energy levels—relevant for fireworks production.

Visual Representation

  • Bohr Model:

    • Depicts nucleus at the center with electron shells around it.

    • Shells are depicted as concentric circles around the nucleus, reflecting increasing energy levels.

Filling Electron Shells

  • Shells (Energy Levels):

    • K shell: Lowest energy level, holds 2 electrons.

    • L shell: 2nd energy level, holds 8 electrons.

    • M shell: 3rd energy level, holds up to 18 electrons.

    • N shell: 4th energy level, holds up to 32 electrons.

Electron Configuration of Elements

  • Hydrogen (H): 1 electron in shell 1.

  • Helium (He): 2 electrons in shell 1.

  • Lithium (Li): 2 in shell 1, 1 in shell 2.

  • Beryllium (Be): 2 in shell 1, 2 in shell 2.

Progression of Electron Filling

  • Boron (B): 2, 3

  • Carbon (C): 2, 4

  • Nitrogen (N): 2, 5

  • Oxygen (O): 2, 6

  • Fluorine (F): 2, 7

  • Neon (Ne): 2, 8

More Elements

  • Sodium (Na): 2, 8, 1

  • Magnesium (Mg): 2, 8, 2.

  • Aluminium (Al): 2, 8, 3.

  • Silicon (Si): 2, 8, 4.

Further Elements

  • Phosphorus (P): 2, 8, 5

  • Sulfur (S): 2, 8, 6

  • Chlorine (Cl): 2, 8, 7

  • Argon (Ar): 2, 8, 8.

  • Potassium (K): 2, 8, 8, 1

  • Calcium (Ca): 2, 8, 8, 2

First Twenty Elements Configuration

  • Configured Listing:

    • Hydrogen: 1,0,0,0

    • Helium: 2,0,0,0

    • Lithium: 2,1,0,0

    • Beryllium: 2,2,0,0

    • Boron: 2,3,0,0

    • Carbon: 2,4,0,0

    • Nitrogen: 2,5,0,0

    • Oxygen: 2,6,0,0

    • Fluorine: 2,7,0,0

    • Neon: 2,8,0,0

    • Sodium: 2,8,1,0

    • Magnesium: 2,8,2,0

    • Aluminium: 2,8,3,0

    • Silicon: 2,8,4,0

    • Phosphorus: 2,8,5,0

    • Sulfur: 2,8,6,0

    • Chlorine: 2,8,7,0

    • Argon: 2,8,8,0

    • Potassium: 2,8,8,1

    • Calcium: 2,8,8,2

Valence Electrons

  • Definition: The electrons in the outermost shell of an atom are the valence electrons, determining the chemical reactivity of the element.

Specific Atoms Structure

Hydrogen

  • Proton: 1, Electron: 1, Neutron: 0

Helium

  • Protons: 2, Electrons: 2, Neutrons: 2

Beryllium

  • Protons: 4, Electrons: 4, Neutrons: 5

Boron

  • Protons: 5, Electrons: 5, Neutrons: 6

Carbon

  • Protons: 6, Electrons: 6, Neutrons: 6

Nitrogen

  • Protons: 7, Electrons: 7, Neutrons: 7

Oxygen

  • Protons: 8, Electrons: 8, Neutrons: 8

Fluorine

  • Protons: 9, Electrons: 9, Neutrons: 10

Neon

  • Protons: 10, Electrons: 10, Neutrons: 10

Sodium

  • Protons: 11, Electrons: 11, Neutrons: 12

Periodic Table Fundamentals

  • Arrangement: Elements are grouped by their properties; horizontal rows are periods, and vertical columns are groups.

  • Group Characteristics:

    • Elements in the same group have similar properties and the same number of electrons in the outer shell.

    • Reactivity trends and similar physical and chemical behaviors within groups.

Noble Gases - Group VIII

  • Reactivity: Very unreactive due to complete outer electron shells.

  • Chemical Bonds: Generally do not form bonds as they naturally exist as single atoms with stable configurations of 8 electrons in the outer shell.