Properties of Atoms and the Periodic Table Chapter 19 Properties of Atoms and the Periodic Table

19.1 – Structure of the Atom Scientific Shorthand Chemical Symbol – letter or pair of letters used to abbreviate the name of an element One capital letter Example: Hydrogen – H One capital letter plus one or two lowercase letters Example: Aluminum – Al Example: Ununbium – Uub Some symbols come from Latin words Example: Argentum is Latin for Silver - Ag

Atomic Components Atom – the smallest piece of matter that still retains the property of the element Example: silver is made up of only silver atoms Atoms are composed of 3 particles. Protons – positively charged Neutrons – neutral Electrons – negatively charged

Nucleus Small, positively-charged center of the atom Where protons and neutrons are found Surrounded by electron cloud Electron cloud The area around the nucleus where electrons are found Electron’s have a small mass and move quickly around the nucleus An electron cloud is a blur of all of the electrons within an atom

There is a worksheet to go with this Meet the Elements Song There is a worksheet to go with this http://www.youtube.com/watch?v=G-wf8S9vRvo

19.2 – Masses of Atoms Atomic Number The number of protons in an atom. Example: Oxygen – atomic number is 8, therefore it has 8 protons The number of protons is equal to the number of electrons Example: Oxygen – has 8 protons it has 8 electrons Mass number The sum of the number of protons and neutrons Number of neutrons = mass number – atomic number

Isotope Atoms of the same element that have different numbers of neutrons Example: Carbon, Atomic number 6 Carbon-12 = 6 protons, 6 neutrons Carbon-13 = 6 protons, 7 neutrons Carbon-14 = 6 protons, 8 neutrons

Isotope Symbol Atomic Number Mass Number Protons Electrons Neutrons Boron-11 B 5 11 6 Carbon-12 C 12 Oxygen-16 O 8 16 Sodium-23 Na 23 Copper-63 Cu 29 63 34

19.3 – The Periodic Table Organizing the Elements Periodic table – arrangement of elements based on increasing atomic number and changes in physical and chemical properties Periodic Law – when arranged in this way, repeating patterns of physical and chemical properties are observed. This is the basis for families of elements.

There are 3 major regions on the periodic table Metals Metalloids Nonmetals

Metals Exist as solids at room temperature Shiny Can be drawn into wires Can be pounded into sheets Good conductors of heat and electricity Color – Gray, silver, yellow Examples: Iron Zinc Copper

Nonmetals On the right side of the periodic table (except hydrogen) Many are gases, but some are solids and one liquid (Br) Brittle and dull Poor conductors of heat and electricity Colors – variety Examples: Oxygen Bromine Carbon

Metalloids Located next to the stair step line Also called semimetals Have some properties of both metals and nonmetals Shiny Good conductor of electricity but not of heat Color – gray or silver Examples: Boron Silicon

Learning Check 1: Classify each element as a metal, nonmetal or metalloid A.Mercury B. Boron C. Iodine D. Aluminum E. Neon F. Barium G. Germanium Metal Metalloid Nonmetal Metal Nonmetal Metal Metalloid

Organizing the Periodic Table Groups – The vertical columns in the periodic table Numbered 1 through 18 Elements in each group have similar properties Example: Group 11 – copper, silver, and gold Shiny metal Good conductor of electricity and heat

Rows on the Periodic Table Periods – horizontal rows of elements on the periodic table The elements increase by 1 proton and 1 electron as you go from left to right in a period. Their properties change in a predictable manner

Groups 18 1 1 13 14 15 16 17 2 2 Periods 3 3 4 5 6 7 8 9 10 11 12 4 5 6 7

There are 4 Major Groups Group 1: Alkali metals (excludes hydrogen) Group 2: Alkaline earth metals Group 17: Halogens Group 18: Noble Gases

Noble Gases Alkali metals Halogens Alkaline Earth Metals

Group 1: Alkali Metals “Alkali” means basic (opposite of acid) These elements react with water to make bases These are soft shiny metals that are gray in color. Examples: Sodium, Lithium http://www.youtube.com/watch?v=uixxJtJPVXk

Group 2: Alkaline Earth Metals “Alkaline” also means basic “Earth” because they are common in the earth’s crust These elements are less reactive than the alkali metals but still react with water to produce bases. Examples: Calcium, Magnesium

Group 17: Halogens “halo” means salt “gen” means to make or form These elements react with metals to produce salts Example: chlorine (Sodium chloride or calcium chloride are the salts produced) Example: Fluorine (sodium fluoride is in toothpaste) http://www.youtube.com/watch?v=2mzDwgyk6QM

Group 18: Noble Gases “Noble” like the kings and queens…too good to react with the common elements Also called the inert gases because “inert” means not reactive. These elements are highly stable and only form a few compounds.