Electronic configurations

Atomic Structure and Electronic Configuration

  • Label the structure of an atom in terms of neutrons, electrons, and protons (C)

  • Identify atomic numbers and mass numbers (B)

  • Draw electronic configurations of atoms (A-A*)

  • Elements in the Periodic Table: Engage in true or false questions to recall knowledge about periodic elements.

True/False Questions

  1. The chemical symbol for sodium is Na. True

  2. A “group” goes across a periodic table. False

  3. Elements in the same group have similar properties. True

  4. The chemical symbol for potassium is P. False

  5. The atom is the smallest particle. False!

Subatomic Particles

  • Definition: Atoms consist of smaller subatomic particles: protons, neutrons, and electrons.

    • Protons: + Charge

    • Neutrons: 0 Charge

    • Electrons: - Charge

Distribution of Subatomic Particles

  • The nucleus contains protons and neutrons at the center of the atom.

  • Electrons orbit the nucleus in layers known as shells.

Labeling an Atom

  • Diagram Labeling Activity: Use whiteboards to label components of an atom, including:

    • Neutrons

    • Protons

    • Electrons

    • Shell

Atomic Number

  • Concept: The atomic number (or proton number) indicates the number of protons in an atom.

  • It is the smaller number typically displayed in periodic tables.

Atomic Number Examples

  1. Sodium (Na): Atomic Number = 11

  2. Iron (Fe): Atomic Number = 26

  3. Tin (Sn): Atomic Number = 50

  4. Fluorine (F): Atomic Number = 9

Mass Number

  • Definition: The mass number is the total number of protons and neutrons in an atom's nucleus; electrons have negligible mass.

  • Formula:
    extmassnumber=extprotons+extneutronsext{mass number} = ext{protons} + ext{neutrons}

Calculating Number of Neutrons

  • Formula:
    extNumberofneutrons=extmassnumber−extatomicnumberext{Number of neutrons} = ext{mass number} - ext{atomic number}

Neutron Examples

  1. Helium (He):

    • Mass Number = 4, Atomic Number = 2

    • Neutrons = 4 - 2 = 2

  2. Fluorine (F):

    • Mass Number = 19, Atomic Number = 9

    • Neutrons = 19 - 9 = 10

  3. Lithium (Li):

    • Mass Number = 7, Atomic Number = 3

    • Neutrons = 7 - 3 = 4

  4. Potassium (K):

    • Mass Number = 39, Atomic Number = 19

    • Neutrons = 39 - 19 = 20

  5. Aluminium (Al):

    • Mass Number = 27, Atomic Number = 13

    • Neutrons = 27 - 13 = 14

Electron Configuration

  • Definition: The arrangement of electrons in an atom's shells

  • Shell Structure:

    • 1st Shell: Holds a maximum of 2 electrons

    • 2nd Shell: Holds a maximum of 8 electrons

    • 3rd Shell: Holds a maximum of 8 electrons

Electron Arrangement in Sodium (Na)

  • Sodium has 3 electron shells:

    • 1st Shell: 2 electrons

    • 2nd Shell: 8 electrons

    • 3rd Shell: Remaining 1 electron

  • Electronic Configuration of Sodium: 2.8.12.8.1

Drawing Electron Configurations

  • First 5 Elements:

    1. Hydrogen (H)

    2. Helium (He)

    3. Lithium (Li)

    4. Beryllium (Be)

    5. Boron (B)

Reminder Questions

  • On a slip, indicate:

    • What you have learned.

    • What you need more help with.

Plenary Questions

  1. Name 3 subatomic particles.

  2. Identify the two numbers given on a periodic table.

  3. What is the maximum number of electrons in shell 1?

Review Learning Objectives

  • Revisit Learning Objectives:

    • Label the structure of an atom

    • Identify atomic and mass numbers

    • Draw electron configurations of atoms