UNIT 2 CHEMISTRY IN ACTION Mr.Yeung
ATOMS REVIEW Check out the Scale of the Universe http://htwins.net/scale2/ Keep the following questions in mind: 1. Are cells bigger or smaller than atoms? 2. Generally speaking, are atoms smaller than everything? 3. When atoms are combined with other atoms, what kind of items do you get? Don t copy this down. Just read and think about the questions.
ATOMS REVIEW Everything is made up of atoms. When we breakdown everything (cells, protein, tables, fuel, gasoline, breath of air, nails, hormones etc ), we get a combination of atoms joined together. There are different versions of atoms that form the different elements we have in our entire Universe. Everything in the Universe is made up from the combination of different elements found in the table below!
WHAT ARE ELEMENTS? Elements are the different versions or flavours that atoms can have. Think of atoms as a single Lego piece Think of elements as the different types of pieces Every element has their own unique characteristic or properties
When different atoms are joined together, they form something. That something can be made up of 1 kind of atoms joined together or a bunch of different kinds joined together 1 Kind of Lego pieces or 1 kind of Element joined together forming a pure substance Different kinds of Lego pieces joined together, or different kinds of elements combined with each other forming compounds or molecules.
EXAMPLES OF ELEMENTS Oxygen, Carbon, Lead, Hydrogen, Lithium, Gold, Silver, Platinum, etc Everything listed on your Periodic Table ARE Elements hence the Periodic Table of Elements! Elements cannot be broken down any further. They are the simplest broken down type of matter. If we were to break down a bar of gold, you would have all gold atoms.
ELEMENT OR NOT AN ELEMENT? Chlorine? Aluminum? Water? Carbon dioxide? Tin? Nitrogen? DNA? Cell? Yes Yes No made up of 2 different types (Hydrogen and Oxygen) No made up of 2 different types (Carbon and oxygen) Yes Yes No made up of billions of atoms of many elements No made up of gallizions of atoms of
BRAINPOP What are atoms? http://www.brainpop.com/science/matter andchemistry/atoms/ What do atoms look like? Atomic model http://www.brainpop.com/science/matter andchemistry/atomicmodel/
PERIODIC TABLE OF ELEMENTS This is the periodic table of elements All elements known to man are arranged in this chart. Elements are a substance that cannot be broken down further, so elements are atoms. Examples: Oxygen, Aluminum, Calcium are all elements
FIND THE FOLLOWING IN YOUR TABLE. Aluminum Oxygen Calcium Neon What are their numbers?
FIND THE FOLLOWING IN YOUR TABLE. Aluminum - 13 Oxygen - 8 Calcium - 20 Neon - 10 These are the atomic numbers, elements are arranged by their atomic numbers, from 1 to 114
What are atomic numbers? Where do they get these numbers from?
STRUCTURE OF AN ATOM There are 3 subatomic particles: 1) protons 2) electrons 3) neutrons Protons: have a positive charge, are in the nucleus, and equals the atomic number Electrons: have a negative charge, are on orbits around the nucleus, and equals the atomic number (in pure atoms, not ions) Neutrons: have no charge, are in the nucleus, and equals the mass number minus the atomic number
Electrons on outside Nucleus has Protons and Neutrons
The Atomic Number is the big number in the top of each element box The Mass Number is the small number under the element s symbol ex: N 7 14.01 Atomic Number Element Symbol Mass Number Protons = Electrons = 7 Neutrons = 14.01 7 = 7.01 = 7
HOW IS THE PERIODIC TABLE ARRANGED?
THE PERIODIC TABLE There are 8 main groups on the periodic table. Groups are the columns (up and down). Periods are the rows (left and right). Alkali Metals are the elements in the first column. Alkaline Earth Metals are the elements in the second column. Chalcogens are the elements in the sixth column.
Halogens are the elements in the 7 th column. Noble Gases are the elements in the last (8 th ) column.
Groups go up and down.
1 2 3 4 5 6 7 8
WHAT DO THESE COLUMNS TELL US? Tells you how many valence electrons there are. Valence electrons Found on the outer most shell of an atom Only valence electrons combine or transfer into other atoms to form bonds In elements other than transition metals, there can only be a maximum of 8 valence electrons Group 1 has 1 valence electron, group 2 has 2 valence electrons, etc
BOHR DIAGRAMS Bohr diagrams show electrons in circular shells 1 st shell has a maximum of 2 electrons 2 nd and 3 rd shells have maximum of 2 electrons The electron number on the outer most shell are your valence electrons. 14 electrons on the outside
DRAW BOHR DIAGRAM OF BORON AND SILICON
WHY ARE VALENCE ELECTRONS IMPORTANT? An element is happy when it has a full valence shell of 8 electrons (like the noble gases) Elements will try to lose 1 or gain 1 valence electron on its valence shell. Ex. Sodium has 1 valence electron, so it will try to form bonds. Ex. Cl has 7 valence electrons, so it will try to gain 1.