Atomic Structure

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Atomic Structure
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Atomic Structure

• Atoms are the basic building blocks of matter
  that make up everyday objects. A desk, the air,
  even you are made up of atoms! There are 90
  naturally occurring kinds of atoms. Scientists in
  labs have been able to make about 25 more.

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Atomic Structure

• There are 3 particles that make up atoms
• 1) Protons
• 2) Neutrons
• 3) Electrons

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Atomic Structure

• 1) Protons
• a) Have a positive charge
• b) Are in the atoms nucleus (the central
  part of the atom)

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Atomic Structure

• 2) Neutrons
• a) Are neutral (no charge)
• b) Are in the atoms nucleus

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Atomic Structure

• When scientists discovered the proton and the
  neutron, they thought there was nothing smaller
  within the atoms nucleus. They were wrong!! In
  1968, scientists discovered new particles inside
  the proton and neutron called quarks.

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Atomic Structure

• There are three quarks in each proton and
  neutron. The quarks are held to each other by
  other particles called gluons.

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Atomic Structure

• 3) Electrons
• a) Have a negative charge
• b) Circle the nucleus in orbitals (rings)

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Atomic Structure

• Different orbitals can hold different numbers of
  electrons. For example, the 1st level can hold
  up to 2 electrons, the 2nd level can hold up to 8
  electrons, the 3rd level can hold up to 18
  electrons, and the 4th level can hold up to 32
  electrons.

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Atomic Structure

• So, if an atom has 20 electrons
• 2 will go on level 1
• 8 will go on level 2 (now we have 10)
• 10 will go on level 3 (now we have 20)
• Just because the level can hold 18, doesnt
  mean there are that many electrons!

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Atomic Structure
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Periodic Table of Elements
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Periodic Table of Elements

• Atoms make up elements. A list of elements are
  found on the periodic table. For every element,
  the periodic table can tell us many things

Atomic Number
Symbol
Atomic Mass
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Periodic Table of Elements

• The atomic mass of an atom tells us the mass of
  the nucleus. In other words, it tells us how
  many protons and neutrons are in the atom.

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Periodic Table of Elements

• The atomic number of an atom tells us how many
  protons are in an atom. In a neutral (uncharged)
  atom, the number of protons is equal to the
  number of electrons. That way the positive and
  negative charges cancel out to give the atom a
  charge of zero. For our purposes, we will only
  be working with neutral atoms.

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Periodic Table of Elements

• So, now we know how many protons are in an atom
  (atomic number) and how many electrons are in an
  atom (same as number of protons). Knowing this,
  we can calculate the number of neutrons.
• We know that the atomic mass of an atom is its
  number of protons neutrons. So, to calculate
  the number of neutrons, we simply subtract the
  number of protons from the atomic mass!

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Periodic Table of Elements

• Using the periodic table of elements, you should
  be able to calculate the number of protons,
  neutrons, and electrons in any atom.
• Lets try this with the element Nitrogen. Looking
  at your periodic table, can you determine how
  many protons, electrons, and neutrons Nitrogen
  has?

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Periodic Table of Elements

• A few more cool facts
• You can never add a proton to an atom of an
  element. Adding a proton changes the element!
• You can add or take away a neutron from an
  atom. Doing this just makes what we call an
  isotope.
• You can add or take away an electron from an
  atom. Doing this makes the atom positive or
  negative.