Scientific Method and Chemistry: An Introduction to Matter and Atoms

Scientific Method

Ask a question.

Research.

Make a hypothesis.

Experiment and test your hypothesis.

Analyze your test results.

Present a conclusion.

Chemistry

Chemistry is the branch of science that studies the properties of matter and how matter interacts with energy.

Organic Chemistry

The branch of chemistry concerned with the study of compounds that contain the element carbon.

Inorganic Chemistry

The branch of chemistry concerned with the study of materials that contain any combination of chemical elements.

Element

A substance that cannot be broken into two or more simpler substances by any physical or chemical method and made of the same kind of atoms.

Compound

A molecule of a pure substance that contains two or more elements combined.

Heterogeneous Mixture

A substance that can be easily separated into its parts, and those parts retain their original properties.

Homogeneous Mixture

One that's mixed or blended together so well that all of the ingredients will not separate out.

Solution

A mixture where one of the substances dissolves in the other. The substance that dissolves is called the solute. The substance that does not dissolve is called the solvent.

Alloy

A mixture of elements that has the characteristic of a metal. At least one of the elements mixed is a metal.

Suspension

A mixture between a liquid and particles of a solid. In this case, the particles do not dissolve.

Colloid

A mixture where very small particles of one substance are evenly distributed throughout another substance.

Atomic Models

Democritus

He claimed that matter was made of small, hard particles that he called 'atoms'.

John Dalton

Atomic model based on Democritus' idea:

• Atoms are tiny, indivisible particles.
• Atoms of one element are all the same.
• Atoms of different elements are different.
• Compounds form by combining atoms.

J.J. Thomson

He discovered electrons and showed that the atom was made of even smaller particles. Plum Pudding Model: Atoms are made mostly out of positive charged material and the negative charged electrons are found inside the positive matter.

Ernest Rutherford

He discovered the protons and the nucleus. He showed that atoms have positive particles in the center, and that atoms are mostly empty space.

Niels Bohr

He proposed that electrons move around the nucleus in specific layers or shells. Every atom has a specific number of electron shells. Planetary model.

Chadwick

He discovered neutrons.

Heisenberg & Schrödinger

They discovered that the electrons behave as waves and move around the nucleus in a cloud. Quantum Mechanical Model.