Atoms and Atomic Theory

Essential Questions: How and why has the Atomic Theory changed over time? How can we describe the molecular motion of the states of matter?

Objectives0 Students will explain that atoms are the smallest unit

of an element and are composed of subatomic particles.

0 Students will analyze models of the scientific theory of atoms.

0 Students will analyze models and describe the motion of particles in solids, liquids, and/or gasses.

Agenda0Bell Ringer0Atoms PowerPoint

0Interactive Notebook Notes0Think-Pair-Share

0Brain Pop: Atomic Theory0Gallery Walk Activity0Independent Practice

Atoms0 Matter is anything that takes up space and has mass.

All matter is made of atoms. 0 Atoms are the basic building blocks of matter. They

make up everything around us; Your desk, the board, your body, everything is made of atoms!

0 Atoms are too small to see without powerful microscopes.

Atomic StructureThere are two basic components in every atom:

Electron Cloud

Nucleus

Subatomic Particles

Three subatomic particles make up every atom:

Subatomic Particle Charge Location

Proton Positive (+) Nucleus or “Core”

Neutron No Charge (0) Nucleus or “Core”

Electron Negative (-) Electron Cloud

Subatomic Particles

Electron Cloud:• Electrons orbit the

nucleus.

Nucleus or “Core”:• Protons and

Neutrons are found in the nucleus.

Atomic TheoryChanges over time…

Atomic Theory0 Because we can not see atoms, we use models to teach

and learn about atoms. 0 The atomic theory has changed over time as new

technologies have become available.

0 Remember: Scientific knowledge builds on past research and experimentation.

Atomic Theory Timeline

Scientist Information Model

John Dalton

All matter is made of atoms. Atoms are too small to see, indivisible and indestructible. All atoms of a given element are identical.

Scientist Information Model

J.J Thompson

Discovered the negative electron, and predicted that there also must be a positive particle to hold the electrons in place.

Atomic Theory Timeline

Scientist Information Model

Ernest Rutherford

Discovered the nucleus of an atom and named the positive particles in the nucleus “protons”. Concluded that electrons are scattered in empty space around the nucleus.

Atomic Theory Timeline

Scientist Information Model

James Chadwick

Discovered that neutrons were also located in the nucleus of an atoms and that they contain no charge.

Atomic Theory Timeline

Neutrons

Atomic Theory Timeline

Scientist Information Model

Neils Bohr

Concluded that electrons are located in planet-like orbits around the nucleus in certain energy levels.

Scientist Information Model(Many Scientists!)The Modern Atomic Theory

Electrons do not orbit the nucleus in neat planet-like orbits but move at high speeds in an electron cloud around the nucleus.

Think-Pair-Share!

Take a minute to read the essential question as I read it aloud: “How and why has the Atomic Theory changed over time?”After you have jotted down your notes in the space on your guided notes, exchange your thoughts with your partner. We will have share-outs and discuss the answer.

http://www.brainpop.com/science/matterandchemistry/atomicmodel/

Atoms and Atomic Theory

Essential Questions: How and why has the Atomic Theory changed over time? How can we describe the molecular motion of the states of matter?

© Boardworks Ltd 20041 of 20 © Boardworks Ltd 200519 of 25

Three states of matter

solid liquid gas

At room temperature most substances exist in one of three physical states.

Solids0 The particles in a solid are very tightly packed and

vibrate in place. 0 Solids have a definite volume and shape.

© Boardworks Ltd 20041 of 20 © Boardworks Ltd 200522 of 25

Particles in a solid – animation

Liquids0 The particles in a liquid are close together but can

move and flow past one another.0 Liquids have a definite volume but they do not have a

definite shape. This is why liquids like water take the shape of the container they are in.

Picture was taken at the exact moment these water balloons were popped!

© Boardworks Ltd 20041 of 20 © Boardworks Ltd 200524 of 25

Particles in a liquid – animation

Gases0 Particles in a gas have higher amounts of energy than

those in a solid or liquid. 0 Gases do not have a definite shape or volume. When

placed in a container, it fills up the entire container and spreads out as far as possible.

© Boardworks Ltd 20041 of 20 © Boardworks Ltd 200526 of 25

Particles in a gas – animation

Molecular MotionAdding heat

Removing heat

In your groups, you will rotate clockwise after 4 minutes through the 5 stations. You will write all information on the Gallery Walk handout.

Stay with your group at all times. Do not move ahead or go back, wait for the timer to move. You may discuss possible answers with your group

members. Raise your hand if you need assistance after you have

asked your group members.

Independent Practice