What is for chapter 3 in McDougal Littell's 'World of Chemistry' textbook?

3.1 The ElementsAbout 100 elements make up all the matter of the universe, 9 of which make up 98% of Earth's atmosphere, crust, and ocean, while oxygen, carbon, hydrogen, and nitrogen make up most of the human body.

Each element has a name and a symbol. The symbol is usually the element's first one or two letters or from the element's original Greek or Latin name.

3.2 Atoms and CompoundsThe Law of constant composition says that a compound always the same proportion by mass of its own elements.

John Dalton's theory:

• Atoms make up all elements.
• All atoms of an element are identical.
• Atoms of different elements are different.
• Compounds consist of atoms different by elements.
• Atom aren't generated or destroyed by a chemical reaction, which only changes the way the atoms are bonded.

A compound's components are shown by a chemical formula, which shows the element types and amounts via symbols and subscripts.

IE: C6H12O6 is a monosaccharide/sugar molecule.

3.3 Atomic StructureJ. J. Thomson and Ernest Rutherford's experiments revealed that atoms have internal structure: an atom has a nucleus, which is the atom's center, contains positively charged protons and neutral neutrons, and negative electrons (about 1/1836 of the protons' mass) that randomly orbit the nucleus with equal charge to protons in terms of strength.

Isotopes are atoms of the same element but with different numbers of neutrons.

IE: Carbon-12, carbon-13, and carbon-14 are isotopes of carbon.

An isotope is written with ZAX, where Z represents atomic number and A represents Atomic Mass.

IE: sodium-23 is 1123Na.

(The subscript should be right below the superscript number, but WikiAnswers' typing system doesn't allow that.)

3.4 The Periodic TableThe Periodic Table shows all known elements to mankind by order of increasing atomic number and groups elements with similar properties into certain columns.

Most elements are metallic and appear on the left side of the zig-zag.

Nonmetals are on the right side of the table.

Metalloids have some metallic and some nonmetallic properties and appear between the metals and the nonmetals on the table.

3.5 Ions and Their CompoundsAtoms form specific ions by gaining/losing electrons.

Metals usually lose 1 or more electrons to form cations (positive ions).

Nonmetals tend to gain 1 or more electrons to form anions (negative ions), which change their names by combining their root name with -ide.

IE: A sodium cation and a chlorine anion form sodium chloride (known as salt), an ionic compound.

The ion that an atom can form can be predicted by its position on the periodic table.

Alkali metals and alkaline earth metals from 1+ and 2+ cations, respectively.

Halogens and Group 6 atoms form 1- and 2- anions, respectively.

An ionic compound is electrically neutral, so the sum of its ions' charges always equal 0.

IE: sodium sulfide (Na2S) always has 2 sodium cations for every sulfur anion.