Vocabulary

Atom- the smallest particle of an element

Nucleus- the central core of the atom, containing protons and neutrons

Protons- small positively charged particles that are found in the nucleus of an       atom POSITIVE

Neutrons- small uncharged particles that are found in the nucleus of an atom NO CHARGE

Electrons- tiny, negatively charged, high-energy particles that move around outside the nucleus of an atom NEGATIVE

            Valance Electrons- the electrons that are farthest away from the nucleus of an    

            atom and are involved in chemical reactions

Atomic Number-the number of protons in the nucleus of an atom

Atomic Mass- the mass of an atom usually expressed in atomic mass units

Atomic Mass Unit- The atomic mass unit, also called the Dalton after the chemist John Dalton, is a small unit of mass used to express atomic masses

Group- elements in the vertical column of the periodic table. Also called family.

Compound- a substance made of two or more elements chemically combined in a ratio, or proportion

Molecule- the combination of two or more atoms

Electron dot diagram- a representation of the number of valence electrons in an atom, using dots placed around the symbol of an element

Noble gases- any of a group of rare gases that include helium, neon, argon, krypton, xenon, and sometimes radon and that exhibit great stability and extremely low reaction rates

Ion- an atom or group of atoms that has become electrically charged

Ionic bond- the attraction between oppositely charged ions

Ionic compound- ionic compounds are basically defined as being compounds where two or more ions are held next to each other by electrical attraction

Covalent bonds- a chemical bond formed when two atoms share electrons

Double bond- a chemical bond formed when atoms share two pairs of electrons

Molecular compound- a compound consisting of molecules of covalently bonded atoms

Polar- the description of a covalent bond in which electrons are shared unequally, or of a molecule containing polar bonds that do not cancel out

Nonpolar- the description of a covalent bond in which electrons are shared equally, or of a molecule containing polar bonds that do cancel out

Chemical formula- a combination of symbols that represent the elements in a compound

Subscript- a number in a chemical formula that tells the number of atoms in a molecule or the ratio of elements in a compound

Concepts

1)

2) The number of valence electrons is the key to whether or not an atom bonds with another atom. A chemical bond forms between two atoms when valence electrons move between them. Electrons may be transferred from one atoms to another, or they may  be shared between the atoms.

3)

Electron dot diagram(LEWIS)                          Electron shell diagram (BOHR)

4) # of protons = # of electrons

    Atomic number = # of protons and electrons

    Atomic Mass – protons = # of neutrons

5) An atom is the smallest part of an element. An ion is an atom or group of atoms that has become electrically charged

6) Ions form by two elements bonding together. When ions come together they balance out the charges on ions. For example:

7) Ionic bonds are the attraction between oppositely charged ions. Covalent bonds are a chemical bond formed when two atoms share electrons.

8) The properties of ionic compounds include crystal shape, high melting points and electrical conductivity. The properties of molecular compounds are that they have poor conductors of electricity.

9) Ionic bonds are the attraction between oppositely charged ions. Covalent bonds are a chemical bond formed when two atoms share electrons.