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CHEMICAL COMPOUNDS AND FORMULAS. ELEMENTS AN ELEMENT IS A PURE SUBSTANCE CONTAINING ONLY ONE KIND OF ATOM.

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Presentation on theme: "CHEMICAL COMPOUNDS AND FORMULAS. ELEMENTS AN ELEMENT IS A PURE SUBSTANCE CONTAINING ONLY ONE KIND OF ATOM."— Presentation transcript:

1 CHEMICAL COMPOUNDS AND FORMULAS

2 ELEMENTS AN ELEMENT IS A PURE SUBSTANCE CONTAINING ONLY ONE KIND OF ATOM.

3 COMPOUNDS COMPOUNDS: 2 OR MORE ELEMENTS CHEMICALLY COMBINED 2 OR MORE ELEMENTS CHEMICALLY COMBINED CREATES A NEW SUBSTANCE CREATES A NEW SUBSTANCE

4 MOLECULE SUBSTANCE MADE OF TWO OR MORE ATOMS CAN BE THE SAME ELEMENT OR DIFFERENT ELEMENTS

5 ElementMoleculeCompound K Au Fe Pb I 2 O 2 CH 4 H 2 O CH 4 C 6 H 12 O 6 CaCO 3 COMPOUNDS, MOLECULES, AND ELEMENTS Compare and Contrast Molecules and Compounds What do you notice? Compounds are 2 or more different atoms Molecules are 2 or more atoms (can be the same or different)

6 CHEMICAL COMPOUNDS TWO OR MORE ELEMENTS CHEMICALLY COMBINED AND FORMED BY CHEMICAL BONDS BETWEEN ATOMS. IONIC BONDS: FORM IONS – COVALENT BONDS: FORM MOLECULES COMPOUNDS HAVE UNIQUE CHEMICAL AND PHYSICAL PROPERTIES. THE PROPERTIES OF COMPOUNDS ARE VERY DIFFERENT FROM THE PROPERTIES OF THE INDIVIDUAL ELEMENTS.

7 CHEMICAL FORMULAS compounds Chemical formulas describe compounds and list the atoms that are present in the compound. NaCl – Sodium chloride (salt) – Na – Sodium, Cl - Chlorine H 2 O – Dihydrogen monoxide (water) – H – Hydrogen, O - Oxygen – CO 2 – Carbon dioxide – C – Carbon, O - Oxygen

8 SUBSCRIPTS NUMBERS WRITTEN BELOW AND TO THE RIGHT OF A CHEMICAL SYMBOL IN A FORMULA. H 2 O – 2 HYDROGEN, 1 OXYGEN H 2 O – 2 HYDROGEN, 1 OXYGEN TELLS HOW MANY ATOMS OF AN ELEMENT ARE IN EACH MOLECULE. TELLS HOW MANY ATOMS OF AN ELEMENT ARE IN EACH MOLECULE. ONLY USED IF MORE THAN ONE ATOM IS PRESENT. ONLY USED IF MORE THAN ONE ATOM IS PRESENT. CAN NEVER BE CHANGED IN A FORMULA CAN NEVER BE CHANGED IN A FORMULA

9 C9H8O4C9H8O4C9H8O4C9H8O4 C = CARBON – 9 ATOMS H = HYDROGEN – 8 ATOMS O = OXYGEN – 4 ATOMS 3 ELEMENTS 21 TOTAL ATOMS

10 H 2 SO 4 H = HYDROGEN – 2 ATOMS S = SULFUR – 1 ATOM O = OXYGEN – 4 ATOMS 3 ELEMENTS 7 ATOMS

11 C 12 H 22 O 11 C = CARBON – 12 ATOMS H = HYDROGEN – 22 ATOMS O = OXYGEN – 11 ATOMS 3 ELEMENTS 45 ATOMS

12 COEFFICIENTS # PLACED IN FRONT OF A CHEMICAL SYMBOL OR FORMULA # PLACED IN FRONT OF A CHEMICAL SYMBOL OR FORMULA IDENTIFIES THE # OF MOLECULES OF A SUBSTANCE IDENTIFIES THE # OF MOLECULES OF A SUBSTANCE 2H 2 O = 2 MOLECULES OF H 2 O 2FEO 3 = 2 MOLECULES OF FEO 3

13 COEFFICIENTS X SUBSCRIPTS TO DETERMINE THE NUMBER OF ATOMS USING COEFFICIENTS YOU MULTIPLY THE COEFFICIENT WITH THE SUBSCRIPT. TO DETERMINE THE NUMBER OF ATOMS USING COEFFICIENTS YOU MULTIPLY THE COEFFICIENT WITH THE SUBSCRIPT. 2H 2 O - 2 MOLECULES OF H 2 O 2H 2 O - 2 MOLECULES OF H 2 O = 4 HYDROGEN ATOMS AND 2 OXYGEN ATOMS

14 2FE 2 O 3 2 MOLECULES OF FE 2 O 3 2 MOLECULES OF FE 2 O 3= 2 X 2 = 4 FE (IRON) ATOMS 2 X 2 = 4 FE (IRON) ATOMS 2 X 3 = 6 O (OXYGEN) ATOMS 2 X 3 = 6 O (OXYGEN) ATOMS

15 COEFFICIENT PRACTICE: HOW MANY ATOMS ARE PRESENT? Carbon: 2 atoms Hydrogen: 8 atoms Hydrogen: 2 atoms Chlorine: 2 atoms Hydrogen: 4 atoms Oxygen: 4 atoms

16 USING PARENTHESES MULTIPLY THE SUBSCRIPT WITH EACH ELEMENT IN PARENTHESES. MULTIPLY THE SUBSCRIPT WITH EACH ELEMENT IN PARENTHESES. AL 2 (SO 4 ) 3 AL 2 (SO 4 ) 3 AL = 2 ATOMS OF ALUMINUM AL = 2 ATOMS OF ALUMINUM S = 3 X 1 = 3 ATOMS OF SULFUR S = 3 X 1 = 3 ATOMS OF SULFUR O = 4 X 3 = 12 ATOMS OF OXYGEN O = 4 X 3 = 12 ATOMS OF OXYGEN

17 (CH 3 ) 2 CHOH C = CARBON = 2X1 = 2+1 = 3 CARBON ATOMS C = CARBON = 2X1 = 2+1 = 3 CARBON ATOMS H = HYDROGEN = 3X2 = 6+2 = 8 HYDROGEN ATOMS H = HYDROGEN = 3X2 = 6+2 = 8 HYDROGEN ATOMS O = OXYGEN = ONLY 1 OXYGEN ATOM O = OXYGEN = ONLY 1 OXYGEN ATOM

18 PARENTHESES Ca H O H O Calcium: 1 atom Oxygen: 2 atoms Hydrogen: 2 atoms

19 Chemical Formulas Check out Potassium Nitrate… How many atoms of potassium are present? KNO 3 How many atoms of nitrogen are present?How many atoms of oxygen are present? Now Ammonium Chloride… NH 4 Cl How many atoms of nitrogen are present? How many atoms of hydrogen are present?How many atoms of chlorine are present?

20 Chemical Formulas Check out Magnesium Hydroxide… How many atoms of magnesium are present? Mg(OH) 2 How many atoms of oxygen are present?How many atoms of hydrogen are present? Let’s take it up a notch… Some formulas involve parenthesis. When this happens, multiply EVERYTHING inside the parenthesis by the subscript that is outside. The subscript outside can NEVER be changed.

21 Chemical Formulas Check out Calcium Phosphate… How many atoms of calcium are present? Ca 3 (PO 4 ) 2 How many atoms of phosphorous are present? How many atoms of oxygen are present?

22 Chemical Formulas Check out the formula for aspirin… How many atoms of carbon are present? 6C 9 H 8 O 4 How many atoms of hydrogen are present? How many atoms of oxygen are present? Let’s take it up a notch again… coefficient The 6 in front of the formula is a coefficient. It tells how many molecules of a compound are present. You multiply the coefficient by EVERYTHING that comes after it.


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