Atoms, Elements, and Periodic Table (Notes)

Atoms, Elements, and

The Periodic Table
(NOTES)

MATTER

• Matter

  • Matter is composed of atoms, which contain subatomic particles that have specific masses, charges, and locations within the atom.

  • Everything is made of matter, and all matter consists of atoms.

ATOMS

• Atoms

  • Composed of subatomic particles: protons, neutrons, and electrons.

    • Subatomic Particles: smaller than an atom

  • An atom has two regions:

    • Nucleus: contains protons and neutrons

    • Electron Cloud: contains electrons

ATOMS

• Protons

  • Positive Charge (+), located in the nucleus

• Neutrons

  • Neutral Charge (0), located in the nucleus

• Electrons

  • Negative Charge (-), located outside the nucleus in the electron cloud

ATOMS

• The electrical charge of an atom is determined by the overall number of protons and electrons in the atom.

  • Examples:

    • Hydrogen atom has one proton and one electron

      • (+1) + (-1) = 0

    • Oxygen atom has eight protons and eight electrons.

      • (+8) + (-8) = 0

  • All atoms on the periodic table have a neutral charge.

ELEMENTS

• Elements

  • An atom is the smallest complete unit of an element.

  • Elements are arranged on the periodic table in increasing order of atomic number.

    • Atomic Number: number of protons in the nucleus of an atom.

ELEMENTS

• For each element on the periodic table, it contains the following information:

  • Atomic Number

  • Element Symbol

  • Atomic Mass (Mass Number)

  • Element Name

PERIODIC TABLE OF ELEMENTS

• Periodic Table of Elements

  • All elements on the periodic table are in order of increasing atomic number.

  • Elements are organized into columns and rows.

    • Groups: columns of the periodic table

      • Elements in the same group possess similar characteristics

      • Elements in the same group have the same number of energy levels

        • Valence Electrons: electrons that are in the outermost energy level of an atom

PERIODIC TABLE OF ELEMENTS

• (Continued - Periodic Table of Elements)

  • Periods: rows of the periodic table

    • Elements in the same period have the same number of energy levels.

    • The period number indicates the number of energy levels.

PERIODIC TABLE OF ELEMENTS

• (Continued - Periodic Table of Elements)

  • The Periodic Table can also be organized into three categories that have similar chemical and physical properties: metals, nonmetals, and metalloids.

    • Metals

      • Metals are usually solid at room temperature

      • Metals are usually shiny, dense, and melt at high temperatures

      • Ductile: stretched into thin wires

      • Malleable: pounded into thin sheets

      • Good conductors of heat and electricity

      • Few valence electrons

PERIODIC TABLE OF ELEMENTS

• (Continued - Periodic Table of Elements)

  • (Continue - Categories of Elements)

    • Nonmetals

      • Nonmetals are dull, low-density, and melt at low temperatures

      • Nonmetals are usually a gas at room temperature

      • Nonmetals cannot change shape easily (brittle)

      • Poor conductors of heat and electricity

PERIODIC TABLE OF ELEMENTS

• (Continued - Periodic Table of Elements)

  • (Continue - Categories of Elements)

    • Metalloids

      • Contains properties of both metals and nonmetals

      • Metalloids can be shiny or dull

      • Metalloids can be ductile and malleable

      • Semiconductors: conducts heat and electricity, but not as good as metals

      • Examples of Metalloids: Boron, Silicon, and Arsenic

PERIODIC TABLE OF ELEMENTS

• (Continued - Periodic Table of Elements)

  • Groups of the Periodic Table (Specific Names of Groups)

    • Group 1 - Alkali Metals

    • Group 2 - Alkaline Earth Metals

    • Groups 3-12 - Transition Metals

    • Group 17 - Halogens

    • Group 18 - Noble Gasses

PERIODIC TABLE OF ELEMENTS

• (Continued - Periodic Table of Elements)

  • Number of Valence Electrons (Electrons in the outermost energy level of an atom)

    • Group 1 - 1 valence electron

    • Group 2 - 2 valence electrons

    • Group 13 - 3 valence electrons

    • Group 14 - 4 valence electrons

    • Group 15 - 5  valence electrons

    • Group 16 - 6 valence electrons

    • Group 17 - 7 valence electrons

    • Group 18 - 8 valence electrons