Chapter 3 notes

Chapter 3.1 Notes Atoms- are the smallest complete particle in an element. Democritus- Greek philosopher that said the universe was made up of atoms. John Dalton- English schoolteacher came up with the atomic theory in Every element is made of atoms that can’t be subdivided. 2.Atoms of the same element are exactly alike 3.Atoms of different elements can join to form molecules.

Nucleus- is the center of an atom; it is made up of protons and neutrons. Proton- is a positively charged subatomic particle in the nucleus of an atom. Neutron- is a neutral subatomic particle that is found in the nucleus of an atom. Electron- a tiny negatively charged subatomic particle that moves around the outside of the nucleus.

Atomic number of an element is the number of protons in the nucleus of each atom of that element. The # of protons = the # of electrons Mass number is the number of protons and neutrons in the nucleus of an isotope. Mass # = p+ + n SOooo n= Mass # - p+ 6 C Carbon Atomic # Symbol Element Mass #

Drawing Atoms Nucleus (center) has 1. element symbol, 2. # of protons (atomic #) 3. # of neutrons (bottom # - top #) Energy Shells have the number of electrons Shell #1 can hold 2 Shell 2-6 can hold 8 Al P+ 13 N 14 e1 e2e3 e4 e5 e6 e7 e8 e9 e10 e11 e12e13

Orbital- or energy shell/level is a region in an atom where there is a high probability of finding electrons. Valence electron- an electron in the outermost energy level of an atom. So in Al valence 3.

Chapter 3.2 Notes Periodic law- properties of elements tend to change in a regular pattern when elements are arranged in order of increasing atomic number, or number of there protons in their atoms.

Period- a horizontal row of elements in the periodic table. Group (family)- a vertical column of elements in the periodic table.

Ion- an atom or group of atoms that has lost or gained one or more electrons from and therefore has a net electric charge. Cation- an ion with a positive charge. Na + Anion- an ion with a negative charge. O -2

Atomic number- the number of protons in the nucleus of an atom. Atomic mass- the total number of protons and neutrons in the nucleus of an atom. Isotopes- any atoms having the same numbers of protons but a different number of neutrons. 5 B Boron Atomic # Symbol Element Name Mass # or Atomic Mass

Atomic mass unit (amu)- a quantity equal to one-twelfth of the mass of a carbon-12 atom. Average atomic mass- the weighted average of the masses of all the naturally occurring isotopes of an element.

Notes Chapter 3.3 Metals- the elements that are good conductors of heat and electricity. Nonmetals- the elements that are usually poor conductors of heat and electricity. Metalloids or Semiconductors- the elements that are intermediate conductors of heat and electricity

Family or groups- vertical columns (18) Period- horizontal rows (7) Metals- Shiny, conduct heat and electricity, can be shaped Nonmetals- brittle, dull, poor conductor Metalloids- have some characteristics of metals and nonmetals. Are semiconductors FAMILYFAMILY PERIOD Metals NON- metals

Family Names Family #1- Alkali metals Family #2- Alkaline-earth metals Families #3-12 Transition metals Family #13 Boron’s Family #14 Carbon’s Family #15 Nitrogen’s Family #16 Oxygen’s Family #17 Halogens Family #18 Noble Gases

Chapter 3.4 Notes Mole- the SI the base unit that describes the amount of substance. (like a dozen) Avogadro’s constant- the number of particles in 1 mol; equals x particles. Molar Mass- the mass in grams of 1 mol of a substance. (mass # off periodic table) Conversion factor- a ratio equal to one that expresses the same quantity in two different ways. 1 dozen = 12 1 dozen dozen

“Atom”. Jan. 7, neral/atom_structure1.jpg neral/atom_structure1.jpg “Periodic Table”. Jan 7, nasaimages/periodic-table.gif nasaimages/periodic-table.gif “Periodic Table”. Jan 9, /periodic_table1.gif /periodic_table1.gif