Protons are positive ( ) charged particles found in the nucleus of an atom.

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Chapter 4 - Part 2

• Protons, neutrons and electrons are all subatomic
  particles.

• Protons are positive () charged particles found
  in the nucleus of an atom.
• Proton mass 1.674 x 10-24g
• 1 proton 1 Charge

Nucleus
Proton
Neutron
Electron
2

• The Neutron
• The neutron is a subatomic particle found in the
  nucleus.
• 1 neutron no charge
• The neutron was discovered in 1932 by James
  Chadwick.
• Its mass is almost the same as a proton.

3

• The Electron
• The electron is a subatomic particle found
  outside of the nucleus of an atom and it has a
  negative (-) charge.
• Electrons mass 9.11 x 10-28g
• 1 electron -1 charge

4
Charge

• A proton has a positive charge 1

• An electron has a negative charge -1

• A neutron is neutral. It wont affect overall
  charge.

• One positive proton will cancel out one negative
  electron leaving an overall charge of Zero

Overall Charge 0
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Complete the table below
Atom ChargeProtons Charge Neutrons Charge Electrons Overall Charge
5 protons6 neutrons5 electrons
16 protons16 neutrons16 electrons
19 protons20 neutrons19 electrons
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The Periodic Table
Elements are organized into rows and columns
based on their atomic number.
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Elements, symbols and masses
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• Atomic Number
• Atomic number of protons for an element.
• Atoms of different elements has different numbers
  of protons.
• Each positive charged proton must be balanced by
  a negative charged electron. So the atomic
  lets you know the of protons and the of
  electrons.
• Example Sulfur (S) is atomic number 16 because
  it has 16 protons. Since it has 16 protons it
  has to have 16 electrons.

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• Mass Number
• The mass number lets you figure out how many
  neutrons are present in an element.
• Mass of protons of neutrons or mpn
• Neutrons mass - atomic since the atomic
  number is the same as the number of protons then
  nm-p

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Mass number continued

• Example Aluminum (Al) has 13 protons.
• Its mass number is 27.
• So, 27-1314 and 14 is the number of neutrons
  found in an atom of Aluminum.

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Atomic Mass Units

• An atomic mass unit (amu) is defined as 1/12th
  of a Carbon-12 atom.

• AMUs is the unit of mass used on the periodic
  table when looking at an elements atomic mass
  number.
• That's about the mass of one proton or neutron.

Protons and Neutrons 1 amu each
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AMUs continued

• 1 atomic mass unit 1.66053886 10-24 kg

• One gram is about 600,000,000,000,000,000,000,000
  amu.
• Ex Fluorines (F) atomic mass is 19 amu, but
  its mass in grams is 3.155 x 10 -28 grams.
• Wow--I can see why you'd want to use amu's
  instead of grams.

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• What is the atomic mass of an atom with
• 4 protons and 5 neutrons
• 24 protons and 28 neutrons
• 7 protons and 7 neutrons
• 91 protons and 140 neutrons

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• Complete the table below

Protons Neutrons Atomic Mass
35 65
10 20
39 70
39 89
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• Isotopes
• Isotopes are atoms of the same element but have a
  different number of neutrons and mass number.

• Example Oxygen (O) has 8 protons but some atoms
  of oxygen have a mass of 16, 17 or 18.
• So this means the number of neutrons varies
  between each isotope. So Oxygen-16 has 8
  neutrons, Oxygen-17 has 9 neutrons and Oxygen-18
  has 10 neutrons.

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• Common Isotopes
• The element Carbon (C) can be found as C12, C13
  and C14.
• How many protons, neutrons and electrons does
  each carbon isotope above have?
• Answer C12 6,6,6
• C13 6,7,6
• C14 6,8,6

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Hydrogen Isotopes

• Hydrogen-1 doesnt have any neutrons.
• Hydrogen-2 has 1 neutron
• Hydrogen-3 has 2 neutrons