Learning Object Info: Lesson Highlight: Topic 1 - The Scientific Method Type: HTML Submitted By: Randall Warwick .
Lesson Highlight: Topic 2 - Fundamentals of Chemistry.
Fundamentals of Chemistry.
When I think of the material things in the world, I like to think of that stuff as substance. However, my British friends don't like it when I use the word stuff. According to them, I should always say things, or material, or perhaps substance - almost anything other than stuff. So here we go. Substance is anything that occupies space and has mass. Substances are diverse: air, water, rock and wood are all substances. Most substances can be broken down into other substances by chemical means. Any substance that cannot be broken down into other substances by ordinary chemical means is called an element. All elements, and thus all substances, are made of fundamental units called atoms. An atom is the smallest unit of an element that shows the properties of that element. For example, an atom of gold is the smallest unit of gold that acts like gold.
If we divide an atom of gold into smaller subunits, we get electrons, neutrons and protons. None of those subunits, which we call subatomic particles, acts like gold. Instead they act like the subatomic particles they are. Thus, each electron acts like any other electron, each neutron acts like any other neutron and each proton has the same properties as any other. For example, every proton in the universe has an atomic mass of one unit and a charge of plus one. Every neutron is electrically neutral with a mass of one atomic mass unit (amu). Electrons are very light (about 1/2,000 amu) and have a charge of negative one.
An atom contains a dense inner region called the nucleus. The nucleus contains the atom's protons and neutrons. The outer region of the atom contains the electrons. The outer region occupied by electrons is much larger than the dense nucleus.
