A2.1 The Periodic Table

Based on their properties… elements can be divided into 3 classes The Elements: There are about 90 naturally occurring elements, and another 25 synthetic elements. Based on their properties… elements can be divided into 3 classes Metals Metalloids Non-Metals

METALS Highly reactive with other substances. Most of the elements are metals METALS Most are solids at room temp Most are silver/grey in colour and shiny All good conductors of heat and electricity Are malleable (shapeable) and ductile (can be stretched)

NON-METALS Exist as solids, liquids or gases at room temperature Only 17 elements are non-metals NON-METALS Grouped together because they lack resemblance to metals…not because they are similar to each other Lots of variation in colour

They are considered the intermediate between the two ends of the Periodic Table All the remaining elements METALLOIDS They have properties that fit with BOTH metals AND non-metals Some conduct electricity, but not very well, or under specific conditions (called semiconductors)

Group IA: Alkali Metals Group IIA: Alkaline Earths Group VIIA: Halogens Group VIIIA: Noble Gases Metals: Nonmetals: Lanthanide Series: AKA rare earths Actinide Series: AKA transuraniums

Notice METALS are on the LEFT SIDE and CENTRE of the table. The Periodic Table The periodic table organizes ALL the elements according to their chemical properties. Notice METALS are on the LEFT SIDE and CENTRE of the table. The NON-METALS are on the FAR-RIGHT. (With one exception – HYDROGEN – which is located on the left side since it often behaves like a metal in chemical reactions) The METALLOIDS are between them, located right along the STAIRCASE LINE.

A Closer Look at your Table Atomic Number Chemical Symbol Chemical Name Atomic Mass Charge in Compound Name in Compound

Organization: The periodic table is organized into rows and columns. Each horizontal line (or row) is called a period. Represents electron arrangement. 1 2 3 4 5 6 7

Organization: Each vertical column forms a group (or family) of elements numbered 1 to 18. The chemical families are groups of elements that have similar chemical and physical properties. 1 18

Families Sodium GROUP 1 – ALKALI METALS - They are soft, shiny and silver in colour - They are the most reactive elements - Francium is the most reactive metal Fr

Families Magnesium GROUP 2 – ALKALINE EARTH METALS - They are shiny and silver in colour, but not soft - They are the second most reactive group - Called “Alkaline" earth metals because they form "alkaline" solutions (OH) when they react with water, so they have a pH greater than seven and are basic.

Families Fluorine GROUP 17 – HALOGENS - These elements are poisonous and react readily - Colored non-metallic elements, colour gets deeper as you move down the group - Fluorine is the most reactive non-metal F

Families Neon GROUP 18 – (INERT) NOBEL GASES - These elements are very unreactive

Lastly... The Staircase separates the metals from the non-metals

Atomic Theory Subatomic Particles An atom is the smallest part of an element that still has the properties of that element Subatomic Particles PROTONS (+) ELECTRONS ( - ) NEUTRONS (no charge)

The Atom has the same # of protons and electrons. Proton/Neutron/Electron Numbers The Atom has the same # of protons and electrons. Atomic Number = number of protons and electrons. Number of Neutrons = Atomic Mass – Atomic number Atomic Number p+ = 35 p+ and e– e– = 35 no = 79.90 – 35 = 44.90 Atomic Mass Round: no = 45 no = Atomic Mass – Atomic Number

Isotopes are Atoms from the same element that contain different numbers of neutrons. Notice in the last example…the no = 44.90 This means that Bromine usually has 45 neutrons , however it can sometimes exist as an isotope with 44 neutrons                                                                         The atomic symbol is sometimes show with the mass number and the atomic number Using this format, the isotopes for Bromine are: and

More Isotopes Isotopes have the same number of protons but different numbers of neutrons Example: Isotopes of Hydrogen Hydrogen Hydrogen Hydrogen (99% of natural (deuterium) (tritium) hydrogen is this found in "Heavy" isotope) water

Examples: 1. Aluminum p+ = 13 e– = 13 no = 26.98 - 13 no = 13.98 Atomic Number = 13 e– = 13 Atomic Mass = 26.98 no = 26.98 - 13 no = 13.98 Note: As an isotope, Aluminum most often exits with 14 neutrons, but sometimes has 13! Round = no = 14 2. Lead

Energy Levels Electrons (-) take up most of the volume of an atom (like 99.9% of it!) and they occupy specific energy levels. An energy level is a space near the nucleus that may be empty OR may contain electrons. Electrons in energy levels near the nucleus have the lowest energy. Energy Levels e - Electrons that are farther away from the nucleus have the more energy. Nucleus

Orbits or Energy Levels Energy Levels of Electrons Valence electrons – the electrons in the outermost energy level * Maximum number of electrons held by each energy level the rest 18e- 18e- 8e- 8e- 2e- Orbits or Energy Levels Energy levels can be empty, partly filled or completely filled! Nucleus

Noble Gases...

SOLUTION! Metals and non-metals can find a mutual solution to their electron's problem!

The Octet Rule: The Rule of Eight states that atoms bond in such a way as to have eight electrons in their valence energy levels. This is another way to say that atoms tend to be stable with full outer energy levels. How many electrons do we need to gain or loose to stay stable??? fluorine neon magnesium

Homework: Read pages 28 – 39 A2.1 Check and Reflect page 39 #’s 1 – 13