Chemistry Ch 5 Atomic Structure

• Subatomic particles include the protons, neutrons, and electrons.

  The protons are positively charged, the neutrons are electrically neutral, and the electrons are negatively charged.
• The electrons move around the nucleus while the protons and neutrons are inside the nucleus.
• In an atom, the amount of protons is equal to the amount of electrons.
• Atoms are electrically neutral.
• The mass number of an element is equal to sum of the number of protons and neutrons.

  The atomic number of an element is equal to the number of protons.

  M(P+N)

  A(P)
• Isotopes are different atoms of the same element which have the same numbers of protons but different numbers of neutrons.
• Elements are classified as metals, non-metals, and semi-metals(metalloids).

  The properties of metals and non-metals vary in terms of state at room temperature and pressure, appearance, melting point and boiling point, density, electrical and thermal conductivity, malleability and ductibility, and hardness and strength
• A hydrogen atom has no neutrons.
• The relative isotopic mass of an isotope of element is the mass number.

  The relative atomic mass of an element is the weighted average of the relative isotopic masses.

  Therefore, the relative atomic mass equals to the mass number times the relative abundance.
• The maximum number of electrons a shell can hold is 2n².