Atomic Structure

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CH 18 Chemistry Of Earth and The Known Universe
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Atomic Structure Subatomic Particles

• Proton- P positive charged - in nucleus
• Number of P distinguishes one atom from another
• Made of 2 up quarks (2/3 charge) and 1 down
  quark (-1/3 charge)
• Neutron- No neutral charged - in nucleus
• Made of 2 down quarks and 1 up quark

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Electrons

• Electron- e- negatively charged - swarming in
  energy levels around nucleus of atom (electron
  cloud).

Electrons (e-) are attracted to the positively
charged protons (P) in the nucleus, helping them
remain close to the nucleus in swarming levels.
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Energy Levels

• Electrons e- have a specific amount of energy
  when in each level.
• K Shell has least energy
• M Shell has most energy (as far as were going)
• e- can occupy only 1 level at a time
• No matter how many levels the outer level
  (valence) can have no more than 8 e-
• Most stable atoms have 8 e- in valence

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18.2 Comparing Atoms

• The number of P determines the type of atom.
  
• If you change the number of P you change the
  atom.

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18.2 Atomic Number

• The Atomic Number is total number of protons in
  the nucleus of an atom.

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18.2 Mass Number

• The total number of protons and neutrons in the
  nucleus of an atom is called the Mass Number or
  Atomic Mass.

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18.2 Isotopes

• Isotopes are atoms of the same element that have
  different numbers of neutrons.
• Each of the below atoms are hydrogen, but they
  are all isotopes of hydrogen.

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Isotopes

• An atom can have 2 or more isotopes
• Isotopes have different numbers of neutrons
• Thus different mass numbers
• More N add mass to atom
• Heavier elements are radioactive (give off N)

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18.3 The Periodic Table of Elements

• Elements are made up of only one kind of atom.
• Compounds are made up of combinations of atoms.
• Elements that are part of the same group act
  alike.

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18.3 The Periodic Table of Elements

• Dimitri Mendeleev (1834- 1907) organized
  information about all the known elements in a
  table that visually organized the similarities
  between them.
• Mendeleev placed each element on the table in a
  certain row and column based on its properties.

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• The chemical symbol is an abbreviation of the
  elements scientific name.