The atomic theory states that all matter is composed of tiny indivisible particles called atoms. Atoms are made up of a small, dense nucleus containing protons and neutrons, surrounded by electrons. Elements are composed of only one type of atom, while compounds are formed when two or more elements chemically bond to form molecules with unique properties different from the constituent elements. The atomic theory provides a model for understanding the structure of atoms and how they combine to form all the variety of matter in the world.

1. Unit 13 Lesson 6 What Is the Atomic Theory?

2. Unit 13 Lesson 6 What Is the Atomic Theory?
A Teeny Tiny Theory
• Substances can be broken down into increasingly
smaller units.
• An atom is the smallest unit of an element that
maintains the properties of that element.
• Atoms are the building blocks of all matter.
• Atoms has 3 particles:
• 1.Protons (+)
• 2.Neutrons (no charge)
• 3.Electrons (-)

3. Unit 13 Lesson 6 What Is the Atomic Theory?
• The atomic theory is a scientific explanation of
the structure of atoms and how they interact with
other atoms.
• Current atomic theory states that:
1- An atom is mostly empty space.
2-At the center of an atom there is Nucleus
surrounded by electrons.
• Nucleus is a small, dense core at the center of
an atom.

4. Unit 13 Lesson 6 What Is the Atomic Theory?
• Nucleus has :
1-A proton is a positively charged particle found in the
nucleus of an atom.
2-Neutrons are particles found in the nucleus, but a
neutron has no charge.
• Nucleus surrounded by:
Electrons are negatively charged particles that speed
through an area around the nucleus called the electron
cloud.

5. Unit 13 Lesson 6 What Is the Atomic Theory?
A Teeny Tiny Theory
• Identify the parts of the atom.

6. Unit 13 Lesson 6 What Is the Atomic Theory?
Molecules
• Many atoms go through chemical change with a
different type of atom and form molecules.
• A molecule is made up of two or more atoms
joined together chemically.
• Similar atoms form elements.
• Ex. Carbon only , oxygen only , gold…etc.
• Different Atoms form compounds.
• Ex. Water molecule , carbon dioxide
molecule

7. Unit 13 Lesson 6 What Is the Atomic Theory?
Elements
• An element is a type of matter made of just one
kind of atom.
• Elements are substances that cannot be
broken into simpler substances.

8. Unit 13 Lesson 6 What Is the Atomic Theory?
Elements
• All atoms of an element have the same number
of protons.
• For example, boron is an element.
• Every atom of boron contains exactly five
protons.
• No other element has atoms with exactly five
protons.
Examples of elements include
neon, mercury, chlorine,
silver, and copper.

9. Unit 13 Lesson 6 What Is the Atomic Theory?
It’s Elementary!
• Electrons are far from the nucleus, so they can be
gained or lost.
• Different atoms of the same element can contain
different numbers of neutrons.
• Protons remain the same, however.
• Examples of elements include neon, mercury,
chlorine, silver, and copper.

10. Unit 13 Lesson 6 What Is the Atomic Theory?
• A compound is a substance formed by atoms
from two or more elements.
• The properties of a compound are often different
from the properties of the elements that form it.
• For example, atoms of carbon and oxygen will
react, forming the compound carbon dioxide.
• This compound has its own properties that are
different than those of carbon or oxygen.

11. Unit 13 Lesson 6 What Is the Atomic Theory?
Putting It All Together
• Which substances are elements? Which
substances are compounds?