5.4 Patterns and the Periodic Table Science 10

The Periodic Table Elements are arranged in the periodic table according to their atomic number. The table is generally arranged with metals towards the left side of the table. Examples of metals are sodium, aluminum, and lithium. Nonmetals are generally found on the right side of the table. Examples of non-metals are carbon, oxygen, and sulfur. One exception is hydrogen which is the lightest element. It behaves mostly as a nonmetal.

Metals and Nonmetals shiny dull malleable brittle conductors Property Metals Nonmetals Lustre Malleability Conductivity Reactivity with acid State at room temperature Tendency to gain or lose electrons Charges of ions formed shiny dull malleable brittle conductors insulators mostly yes no mostly solids solids, liquids, gases lose gain positive negative

Chemical Periods and Groups Groups of elements in the same vertical column of the periodic table are called chemical families. They tend to have similar chemical and physical properties. The rows in the periodic table are known as periods. Family Location Examples Similarities Alkali Metals Alkaline Earth Metals Noble Gases Halogens far left lithium, sodium form compounds, white, soluble group II calcium, barium shiny, insoluble far right helium, neon don’t form compounds 2nd from right fluorine, chlorine poisonous, react with sodium

Periodic Table of the Elements

Elements and Atomic Structure Atoms are composed of three types of subatomic particles. Subatomic Particle Charge Symbol Mass (amu) Location Electron Proton Neutron Around Nucleus 1- e- 1/2000 1+ p+ 1 Nucleus N0 1 Nucleus The farther away an electron is from the nucleus the greater is its energy and the more likely it is to be involved in a chemical change.

Standard Atomic Notation (for a neutral atom) Atomic number Atomic symbol 35 Br 80 Mass number # of protons = Atomic number = 35 p+ # of electrons = Atomic number = 35 e- # of neutrons = Mass number – Atomic number = 80-35 = 45 n0

The Bohr-Rutherford Model Nucleus – contains protons and neutrons Electrons – circle the nucleus in orbits – each electron orbit has a definite or maximum amount of electrons. – the first orbit has two electrons, the second orbit holds eight electrons, and the third orbit holds no more than eight electrons. 2 Helium Atom 2 positive protons in nucleus 2 neutral neutrons in nucleus 2 negatively charged electrons in the first energy level He 4

How to Draw a Bohr-Rutherford Diagram 14 Si 14 electrons and 14 protons Nucleus use the atomic number to determine the protons subtract the mass number and atomic number to determine the neutrons Draw in the energy levels - row # = # orbits Add electrons following the 2-8-8-2 pattern for the first 20 elements 28 28-14 = 14 neutrons 14 p 14 n

Homework Pg. 187 #1-9 Mr. Dee Video Clip: Periodic Table