Lesson 1-2-3, and 4: States of Matter, Physical and Chemical Change, Elements, Compounds, and Mixtures, & Atomic Structure.

What are the three states of matter?

Solid, Liquid, and Gas.

What is a key characteristic of solids?

Particles are packed closely in fixed positions and cannot move.

Can solids be compressed?

No, solids cannot be compressed.

What is a key characteristic of liquids?

Particles are closely packed but can move past each other, no fixed shape but fixed volume.

What happens to liquids when placed in a container?

They take the shape of their container.

What provides gases with high kinetic energy?

Particles in gases are far apart and move freely.

What are physical properties?

Properties observed without changing the composition of the substance.

Give an example of a physical change.

Melting ice.

What are chemical properties or changes?

Properties observed when a material changes into a new substance.

What is a chemical reaction often detected by?

Formation of insoluble products, evolution of gas, or change in color.

What are pure substances?

Substances composed of only one kind of matter, including elements and compounds.

What defines an element?

The only one type of atom in a substance.

What is a compound?

A substance made of two or more different types of elements combined.

Define homogeneous mixture.

A mixture with a uniform composition throughout.

Define heterogeneous mixture.

A mixture with a non-uniform composition.

Who proposed the first atomic theory?

John Dalton.

What does Dalton's atomic theory state about matter?

Matter consists of indivisible atoms and chemical reactions involve rearrangement of these atoms.

What is the mass of a proton in grams?

$1.672 imes 10^{-24}$ grams.

What role do neutrons play in the atomic nucleus?

They stabilize the nucleus by counteracting proton repulsion.

What defines the chemical properties of an element?

The number of protons in the nucleus.

What model did Joseph John Thomson propose?

Plum Pudding Model.