Introduction to the Periodic Table Atomic Number ● Symbol ● Atomic Weight Element ● Compound ● Mixture

Common Misconception  Isotopes – atoms of the same element so they have the same ATOMIC # (protons) & different MASS # (neutrons)  There is not just 1 “regular” atom which you see on the Periodic Table  The symbols on the Periodic Table represent “average” atoms of elements –A sample of an element found in nature contains a mixture of the different isotopes of that element

I am Dmitri Mendeleev! I made the PERIODIC TABLE !

What is the PERIODIC TABLE? o Shows all known elements in the universe. o Organizes the elements by chemical properties.

How do you read the PERIODIC TABLE?

What is the ATOMIC NUMBER? o The number of protons found in the nucleus of an atom Or o The number of electrons surrounding the nucleus of an atom.

What is the SYMBOL? o An abbreviation of the element name.

What is the ATOMIC MASS? o The number of protons & neutrons in the nucleus of an atom.

How do I find the number of protons, electrons, and neutrons in an element using the periodic table? o # of PROTONS = ATOMIC NUMBER o # of ELECTRONS = ATOMIC NUMBER o # of NEUTRONS = ATOMIC _ ATOMIC MASS NUMBER MASS NUMBER

The Periodic Law  Elements are arranged by increasing atomic number (# of Protons)

Periodic Law  Periods – Each row (7 total)  Groups – Each column (32 total) –Properties of elements repeat in a predictable way when atomic numbers are used to arrange elements into groups Pg 131 in the book fig. 6

Groups  Elements in a group have similar electron configurations –Electron configurations determine its chemical properties –Members of a group in the periodic table have similar chemical properties Known as Periodic Law!!!

Elements, Compounds, and Mixtures

What is an ELEMENT? o A substance composed of a single kind of atom. o Cannot be broken down into another substance by chemical or physical means.

What is a COMPOUND? o A substance in which two or more different elements are CHEMICALLY bonded together.

What is a MIXTURE? o Two or more substances that are mixed together but are NOT chemically bonded.

Classes of Elements  Solids, Liquids, or Gases  Elements that occur naturally and those that do not – all but 2 w/ atomic # 1-92 occur on Earth naturally; elements # 93 & higher do not  Metals, Nonmetals, and Metalloids Pg 133 in your textbook

Metals  Good conductors of electric current and heat –Except for Mercury, metals are solid at room temp.

Metals Most solids (Hg is liquid) Luster – shiny. Ductile – drawn into thin wires. Malleable – hammered into sheets. Conductors of heat and electricity. Include transition metals – “bridge” between elements on left & right of table

Transition Metals  Elements that form a bridge between the elements on the left and right sides of the table –Exp. Copper & Silver –Many are able to form compounds with distinctive colors

Nonmetals  Elements that are poor conductors of heat & electric current –Exp. Fluorine is the most reactive

Non-Metals Properties are generally opposite of metals Poor conductors of heat and electricity Low boiling points Many are gases at room temperature Solid, non-metals are brittle (break easily) Chemical properties vary

Metalloids  Elements with properties that fall between those of metals and nonmetals –Ability to conduct electric current varies with temp.

Metalloids stair-step pattern Have properties similar to metals and non-metals Ability to conduct heat and electricity varies with temp Better than non-metals but not metals

Variation Across a Period: Left to Right Physical and Chemical properties Atomic size decreases Metallic properties decrease Ability to lose an electron decreases Ability to gain electrons increases

Review  Elements are arranged by increasing Atomic Number (# of P’s) –Each row = Period –Each column = Group  Properties of elements repeat in a predictable way when atomic #’s are used to arrange elements into groups

Review Continued…  Atomic mass depends on the distribution of an element’s isotopes in nature an the masses of those isotopes  Elements are classified as metals, nonmetals, and metalloids  Across a period from left to right, the elements become less metallic and more nonmetallic in their properties