Compounds and Mixtures 8 th Grade Science SWMS

Compound A chemical substance consisting of two or more different chemical elements Examples: (what elements?) Water = H 2 O Vinegar = CH 3 COOH  Baking Soda = NaHCO 3 ***1***

Chemical Formula Series of chemical symbols used to represent a compound Examples: – Sucrose (C 12 H 22 O 11 ) – Hydrochloric Acid (HCl) – Ethanol (C 2 H 5 OH)  Subscript  Small number used to show number of atoms/elements present **2**

Mixtures Combination of two or more pure substances that are NOT chemically combined. No chemical change (reaction) takes place! – Ex: Tap Water has minerals mixed in

Element, Compound, or Mixture? Copper

Element, Compound, or Mixture? Copper

Element, Compound, or Mixture? Table Sugar

Element, Compound, or Mixture? Table Sugar

Element, Compound, or Mixture? Diamond

Element, Compound, or Mixture? Diamond

Element, Compound, or Mixture? Salt

Element, Compound, or Mixture? Salt

Element, Compound, or Mixture? Salad

Element, Compound, or Mixture? Salad

Element, Compound, or Mixture? Pure Water

Element, Compound, or Mixture? Pure Water

Compounds look different When elements form compounds  Different properties than when uncombined For Example: -Sulfur = Yellow Rock -Silver = Shiny Metal

Silver Sulfide looks different! End Product: Silver (Ag) + Sulfur (S)  Silver Sulfide (Ag 2 S) Silver Sulfide = Black Tarnish

Totaling Atoms Using PSEC Parentheses Subscripts Extras Coefficients Count up the total number of atoms inside the parentheses Multiply the total number of atoms inside the parentheses by the subscript value Add any extra atoms that were not yet accounted for to the total Multiply the total number of atoms (from PSE) by the coefficient

Examples Parentheses Subscripts Extras Coefficients 2Ba(NO 3 ) 2 4(NH 4 ) 3 PO 4 P – 4 atoms total N  1 O  3 4 atoms S – 8 atoms total (4)(2) = 8 atoms E – 9 atoms total = 9 atoms C – 18 atoms total (9)(2) = 18 atoms P – 5 atoms total N  1 H  4 5 atoms S – 15 atoms total (5)(3) = 15 atoms E – 20 atoms total = 20 atoms C – 80 atoms total (20)(4) = 80 atoms

Homework (10/15, 10/16) Search and find 5 common compounds hiding in your house. For each one you will provide: – The common name of the compound – The elements that make up your compound (name and symbol) – How many total atoms in a single molecule of your compound.