Transcript Chapter 16.1

Chapter 16.1
Key Concept: Atoms are the
smallest form of elements
Explore
Cut the strip of paper in half. Cut one of
these halves in half.
 Continue cutting one piece of paper in half
as many times as you can.

How many cuts were you able to make?
 Do you think you could keep cutting the
paper forever? Why or why not?
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I. All matter is made of atoms
A.
Types of atoms in Earth’s Crust and Living
Things
1. How much of the universe do you think
hydrogen atoms mass and account for?
2. Earth’s Crust: Hydrogen, Oxygen, Iron,
Aluminum, Silicon
3. Living Things: (25 types of
atoms/elements) Oxygen, Nitrogen,
Hydrogen, Carbon
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Names and Symbols of Elements
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Each element has its own symbol. Sometimes it is
just the first letter of its name. (Oxygen= O)
 Oxygen= O
 Hydrogen= H
 Carbon= C
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Sometimes the first letter is combined with another
letter in the name
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Aluminum= Al
Platinum= Pt
Cadmium= Cd
Zinc= Zn
II. Each element is made of a different
atom
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The structure of an atom
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Atoms contain charged particles
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Particles with the same charge repel
Particles with opposite charge attract
Proton- a positively charged particle
Neutron- uncharged particle
Electron- negatively charged particle
Protons and Neutrons are grouped together in
the center of the atom, called the nucleus
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Electrons move around the outside of the
nucleus.
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Much smaller than protons or neutrons (2000x)
Move around the nucleus really quickly
Quick Check- What are the major parts of
an atom?
 Atomic Numbers
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Atomic number- the number of protons in the
nucleus
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Atomic Mass Numbers
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Atomic mass number- the total number of
protons and neutrons in an atom’s nucleus
Isotope- atoms of the same element that have
a different number of neutrons.
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Chlorine atoms have 17 protons (always). Some
atoms, however have 18 neutrons and some have 20
Quick Check- How is atomic mass different
from atomic number?
III. Atoms for ions
Ion- formed when an atom loses or gains
one or more electrons
 Formation of Positive Ions
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When an atom loses an electron
Formation of Negative Ions
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When an atom gains an electron