Presentation on theme: "Classifying Matter Matter ElementsCompoundsMixtures Scientists classify matter according to make-up."— Presentation transcript:
Classifying Matter Matter ElementsCompoundsMixtures Scientists classify matter according to make-up.
Elements Simplest pure substance – fixed composition. Pure substance is made of only one material. Same throughout. Referred to as homogeneous matter. Are made of alike atoms, which are the basic building blocks of matter. Represented by chemical symbols - H, O, Al, Cu, Au. 118 elements organized in the periodic table in squares called an element key.
Element Key Atomic Number Symbol Element Name Atomic Mass I.D’s the element represents elements mass of element (amu’s)
Compounds Two or more elements chemically combined. Represented by chemical formulas. Examples: H 2 O, CO 2, NaCl, C 12 H 22 O 11 Molecules are the smallest natural unit of a compound or diatomic element. A molecule is made up of two or more atoms chemically combined.
Chemical Formulas Combination of chemical symbols that represents compounds. Sometimes represents a molecule of an element. Example: O 2, N 2, Cl 2 called diatomic elements – two atoms of the same element. Subscripts are the # of atoms of an element - H 2 O Coefficients are the # placed in front of chemical formula. Represents # of molecules of a compound - 4 H 2 O
Identifying Substances Substance Element or Compound Symbol or Formula Atom or Molecule Fluorine (F) Water (H 2 O) Chlorine gas (Cl 2 ) ElementSymbolAtom CompoundFormula Molecule Element Molecule
Counting Atoms NameUseFormula Atoms in Formula Calcium carbonate ChalkCaCO 3 Magnesium hydroxide Found in milk of magnesia Mg(OH) 2 Phosphoric acid Detergents3H 3 PO 4 Trinitrotoluene (TNT) Explosive2C 7 H 5 (NO 2 ) 3 Ca=1 C=1 O=3 H=9 P=3 O=12 Mg=1 O=2 H=2 C=14 N=6 H=10 O=12
Calculating Formula Mass Formula mass of a compound is the sum of the atomic weights of all atoms in a chemical formula. Examples: Atoms Atomic Mass Totals H 2 O 2 of H 2 x of O 1 x amu C 12 H 22 O of C 12 x of H 22 x of O 11 x amu
Mixtures Two or more substances mixed together but not chemically combined. Has unlike parts and a composition that varies from sample to sample. Properties: – Sub. in a mixture keep their separate identities. – Sub. can be present in any amount. – Sub. can be separated out by physical means.
Heterogeneous Mixtures The least-mixed. Doesn’t appear to be the same throughout. Particles large enough to be seen. Examples: sand, dirt, concrete, suspensions, etc.
Homogeneous Mixtures Well-mixed. Same throughout a given sample. Examples: air, soda, toothpaste, lotions, etc.
Solutions A homogeneous mixture. One substance dissolves in another. Solutions remain constantly & uniformly mixed. Examples: lemonade, soda, ocean water, antifreeze, metal alloys (steel, brass), etc.
Colloids A homogeneous mixture. Mixed together but not dissolved. Appears cloudy. Scatters light. Examples: milk, cool whip, toothpaste, lotions, fog, paint, etc.