2.2.2

Relative Charge, Mass & Atomic Numbers

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Atomic Structure: Relative Charge, Mass & Atomic Numbers

Atoms have protons, neutrons, and tiny electrons. Proton number defines the element. Mass number is protons + neutrons. Relative charge and mass describe particles in the atom.

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Particles in an atom

  • Atoms contain protons, neutrons, and electrons.
    • Protons have a relative charge of +1.
    • Neutrons have no charge, so their relative charge is 0.
    • Electrons have a relative charge of -1.
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Relative mass of particles

  • Protons have a relative mass of 1.
  • Neutrons have a relative mass of 1, similar to protons.
  • Electrons have a much smaller relative mass, about 1/1836.
    • Atoms are mostly mass in their nucleus, where protons and neutrons exist.
Illustrative background for Proton number (Atomic number)Illustrative background for Proton number (Atomic number) ?? "content

Proton number (Atomic number)

  • The proton number is the number of protons in an atom's nucleus.
    • Proton number defines the element (e.g., carbon always has 6 protons).
  • Proton number is also called atomic number.
Illustrative background for Mass number (Nucleon number)Illustrative background for Mass number (Nucleon number) ?? "content

Mass number (Nucleon number)

  • The mass number is the total protons and neutrons in the nucleus.
    • Mass number = number of protons + number of neutrons.
  • This number tells the mass of the nucleus but ignores electrons.
    • Example: Carbon-12 has 6 protons and 6 neutrons, so mass number = 12.
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Summary of atomic numbers and mass

  • Atomic number = number of protons, identifies the element.
  • Mass number = protons + neutrons, which shows the atom's mass.
  • Relative charge and mass help describe particles in the atom.

Jump to other topics

1States of Matter

2Atoms, Elements & Compounds

3Stoichometry

4Electrochemistry

5Chemical Energetics

6Chemical Reactions

7Acids, Bases & Salts

8The Periodic Table

9Metals

10Chemistry of the Environment

11Organic Chemistry

11.1Formulae, Functional Groups & Terminology

11.2Naming Organic Compounds

11.3Fuels

11.4Alkanes

11.5Alkenes

11.6Alcohols

11.7Carboxylic Acids

11.8Polymers

12Experimental Techniques & Chemical Analysis

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