Atoms-Basic Units of Matter

Where did Democritus derive the word atom from?

"Atomos", the Greek word for indivisible.

What is an element?

A pure substance made of one kind of atom.

What is an atom?

A very small part of matter. Specifically, the smallest form of any substance that retains all the qualities of said substance. (See page 175 for more info about atoms.)

When were atoms proposed, and when did evidence of them become available?

About 400 B.C. Within the last 300 years.

How often do the parts of an atom move? What are the three main particles of an atom, and the two spaces?

Constantly. Protons, Neutrons, and Electrons. Nucleus and Energy Levels.

What did Dalton do to simplify common elements?

Dalton created symbols. See p.178 for these.

What makes up most of an atom?

Empty space.

What makes up the nucleus?

Heavy protons with a positive charge and heavy neutrons with no charge.

Who proposed the Law of Definite Proportions, and what is it?

J.L. Proust. Any pure compound always contains the same elements in the same proportion by mass. A simple example of this law: pure water found in Sacramento is identical to pure water found on Mars.

Who proposed the Law of Conservation of Mass, and what is it?

Lavoisier. In normal chemical reactions, mass is neither created nor destroyed.

What are the five principles of today's atomic theory?

Listed, and examples in parentheses. a.All matter is made of atoms. (Everything has atoms in it.) b.Atoms are neither created or destroyed in chemical reactions. (Atoms, or mass in other words, are not changes in chemical reactions.) c.Atoms of different elements combine in whole number ratios. (When two elements combine, they always are in whole numbers. For example, H20 is 2 Hydrogen atoms and 1 Oxygen atom. There can not be H1.50, etc.) d.Each element is made of a different atom. (No two elements have the same numbers of electrons, neutrons, and protons.) e. Atoms of different elements have different masses and properties. (Different atoms have different properties. For example, hydrogen has a lower mass than oxygen.)

What is matter?

Matter is anything that takes up space and has mass. Everything is made of matter.

What are the two types of properties of matter? Explain with an example.

Physical Characteristics that can be observed or measured, like temperature (you can measure temperature). Chemical characteristics, which describe how something will either combine or change into a new substance. One example: oxygen has the characteristic to bond with another oxygen molecule, making O2.

What did Democritus propose atoms were?

Small, solid spheres with no holes or empty spaces. He also proposed they were the smallest piece of a substance that is still purely that substance.

What makes the energy levels?

Very light electrons with a negative charge.