2.1 Early Ideas in Atomic Theory

2.1 Early Ideas in Atomic Theory

The language used in chemistry is used in many disciplines.

The language of chemistry has its own form of shorthand.

Chemical symbols are used to represent elements.

Chemical formulas show the composition of compounds.
Information about the quality and quantity of chemical reactions can be found in chemical equations.

Our study of the language of chemistry will begin with this chapter.

The atomic theory, the composition and mass of an atom, the variability of the composition of isotopes, ion formation, chemical bonds in ionic and covalent compounds, the types of chemical reactions, and the naming of compounds are some of the concepts of this foundation.
The periodic table is one of the most powerful tools for organizing chemical knowledge.

Ancient Greek philosophers were the first to discuss the basic structure of matter.

They thought of atoms as moving particles with different shapes and sizes.
The four elements--fire, earth, air, and water--could be divided into various combinations.
Philosophers thought about atoms and elements as concepts, but never considered performing experiments to test their ideas.

The view of the composition of matter was held sway for two thousand years by the Aristotelian view.

Many of the theories about the tiny features of matter that were first published in 1807 are still valid in modern atomic theory.

Matter is composed of small particles.

The smallest unit of an element can be involved in a chemical change.

An element consists of only one type of atom, which has a mass that is characteristic of the element and is the same for all atoms of that element.

A pre-1982 copper penny contains 3 x 1022 copper atoms, each of which has the same chemical properties.

A compound is composed of atoms of two or more elements.

When the elements copper and oxygen rearrange their atoms, they form a compound containing copper and oxygen.
If an element such as copper has only one kind of atom, it cannot be broken down into simpler substances that are composed of fewer types of atoms.
If atoms are not created or destroyed during a chemical change, the total mass of matter will remain constant.

The green spheres represent elements.

The atoms of another element are represented by purple spheres.
The spheres are part of a compound if they touch.

There are two green and two purple spheres.

During a chemical change, atoms are neither created nor destroyed, but redistributed.

The green spheres represent elements.

The atoms of another element are represented by purple spheres.
The spheres are part of a compound if they touch.

The starting materials are green and purple.

Atoms are neither created nor destroyed, but are redistributed in small, whole-number ratios.

There is a suggestion that the numbers of atoms in a compound are always the same.

Although all samples of a particular compound have the same mass ratio, the converse is not true in general.

Samples with the same mass ratio are not necessarily the same substance.
There are many other compounds that have the same carbon-to-hydrogen mass ratio.

Data from Proust, as well as results from his own experiments, were used to come up with another interesting law.

A green and brown solid with a mass ratio of chlorine to copper and chlorine to copper can be formed, as well as a brown solid with a mass ratio of chlorine to copper and chlorine to copper.

If we take a ratio of these ratios, we get a small, whole-number ratio.

The brown compound has more chlorine per pound of copper than the green compound.

The brown compound has a copper-to-chlorine ratio of 1 copper atom to 2 chlorine atoms, while the green compound has a copper-to-chlorine ratio of 1 copper atom to 1 chlorine atom.

The copper chlorine compound in (b) has twice as many chlorine atoms per copper atom as the copper chlorine compound in (a) does.

A sample of compound A contains 4.27 g carbon and 5.69 g oxygen.

A sample of compound B contains 5.19 g carbon and 13.84 g oxygen.