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Elements are completely pure.
• All Matter is made up of Elements
• They are only made of one type of ATOM
HELIUM ATOM
Element Protons Electrons Neutrons
Na 11 11 12
Cl 17 17 18
Mg 12 12 12
Ne 10 10 10
Ag 47 47 61
Br 35 35 45
Bonus:Ds
110 110 171
Rules for writing element symbols
• Must print• 1st letter capitalized• 2nd letter lower case
Why?
Ex. CO vs. CoCarbon& Oxygen vs Cobalt
AtomSmallest particle of an element
that still has the characteristics of that element
Atom of Sodium
Electron energy levels• Are regions where electrons travel
around the nucleus .• Each energy level can only hold a
certain number of electrons• 1st Shell = 2 electrons• 2nd Shell = 8 electrons• 3rd Shell = 8 electrons
Groups/Families• The elements in a column are called a group.
• Groups are also known as families.
• Elements in a group have similar characteristics.
• The OUTER SHELL = VALENCE SHELL
ADD this sentence
Periods• Each horizontal row is called a period.
• A period contains a series of different type of elements from different family.
• They represent the # of SHELLS.
ADD this sentence
Why the Table Works?
• Elements have different numbers of outer (valence) electrons
• The number of (valence) electrons determines whether it gives up, shares, or accepts other electrons.
• That number of valence electrons an element has increases from left to right known as a period!
Famous FamiliesAlkali Metals• Highly Reactive with water and the
Halogens
• Reactivity increases as you move down the group
Demos
•1 electron in outer shell
Na
Alkali Metals Halogens
Noble Gases
On your big periodic Table:1.Circle and label the three groups above.2.Star the metalloids which are in yellow
Building Blocks of Matter
• Atoms are the building blocks of matter.
molecule
compound
moleculeelement
molecules
•Each compound is made of the same kind of molecule.
•A molecule is made of two or more different kinds of elements that are chemically bonded.
• Each element is made of the same kind of atom.
atom
Compound• Compounds are pure substances
• Only made of one type of molecule!
Example: Sodium Chloride…
Element• Elements are pure substances
• Only made of one type of atom!
Example: Sodium
Counting Elements:
Every Capital letter is the beginning of a new element in the formula.
Capital letter = New element
NaCl = 2 elements: Na & Cl
6 C atoms + 12 H atoms + 6 O atoms = 24 total atoms
Counting Atoms:
A small number, below and to the right of the element symbol, is called a
subscript# = # of atoms
CC66HH1212OO66
Counting Total Atoms in Compounds:
A large number at the beginning of a formula signals that there are two of that molecule.
1. Count the total atoms after the #2
2. Then multiply the group by 2
2 CuSO4
3 Elements6 x 2 =12 total atoms
CuSO4 =6 atoms
Parentheses and subscriptsParentheses and subscripts
1. Add the inside of (parentheses) first.
2. Multiply the ( ) by the subscript.
3. Add the other atoms to your answer
NaH(CO3)4
CO3 + CO3 + CO3 + CO3
4 Elements
18 Total Atoms
Why Chemical Reactions Occur…
Three things to remember:
1. Atoms want to be stable!
2. Atoms with full outer levels are stable
3. Atoms will do anything to become stable!
Chemical Reaction Example
2 types of Chemical “Bonding”
• Covalent bonding: atoms share electrons– Ex. Oxygen (Oxygen bonds with oxygen)
•Ionic: atoms gain or lose an electron –Ex. Chlorine needs one electron and sodium has one extra to give.–This changes their charge and makes NaCl
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