Transcript Chapter 18 – Atoms and Elements

Atomic Structure
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Atomic Structure
– Key Terms and Concepts:
• proton, neutron, electron
• Locations in the atom
What is an Atom?
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The smallest particle of an element
Made up of protons, neutrons, and
electrons
When NEUTRAL, an atom has the same
number of protons and electrons.
When NOT Neutral, the atom has more
or less electrons than protons = called an
ION
Inside an Atom
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Protons: subatomic particle
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Charge: positive
Mass: 1 amu (atomic mass unit)
Location: nucleus
Equal to the Atomic Number on the Periodic Table
Neutrons: subatomic particle
– Charge: neutral (no charge)
– Mass: 1 amu (atomic mass unit)
– Location: nucleus
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Electrons: subatomic particle
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–
–
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Charge: negative
Mass: 0 amu (atomic mass unit)
Location: electron cloud/levels/orbital (outside the nucleus)
Equal to the number of protons in a NEUTRAL atom
What makes one kind of atom
different from another?
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The number of protons determines
the type of atom
– Carbon has 6 protons, Oxygen has 8
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All atoms of the same element
have the same number of protons
– Electrons and neutrons may vary
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Different elements have different
numbers of protons
 Even in chemical reactions, the
atoms stay the same
– they are only arranged in different
ways
How are atoms described?
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Atomic Number
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The number of protons,
determines which element it is
On the periodic table in numerical order
In a neutral atom, it is also the number of electrons
Atomic Mass
– The mass of each = numberof neutrons + number of protons
– Usually the bigger number on the periodic table with a decimal
– The same element may have atoms with different masses
• These are called ISOTOPES
– Isotopes are atoms of the same element with naturally
occurring differences in the number of neutrons
– Has a different mass than what is on the periodic table
• Sometimes isotopes of an element are radioactive
Review and Practice
Subatomic Particles Review – use your
notes if you need to
 Find the Missing Numbers – take 3
minutes to practice on your own
 Compare answers with a partner, correct
or teach – 3 minutes
 Discuss as a class
 On your own, complete Atomic
Structures, raise your hand when you are
finished and I will check your answers
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