Matter Properties and Composition CHM 1010 PGCC Barbara A. Gage

Properties Physical Property - any property that can be observed without transforming the substance into another substance mass, color, freezing point Chemical Property - any property that cannot be studied without transforming the substance into a different substance iron rusts, paper burns CHM 1010 PGCC Barbara A. Gage

Changes Physical Change - change that does not transform the substance into another substance melting, subliming, dissolving CHM 1010 PGCC Barbara A. Gage

Changes Chemical Change - change that transforms the substance into another substance burning, oxidation of metal /CCA/pirelli/pages/cca1NaIHgCl2.html /CCA/pirelli/pages/cca1NaIHgCl2.html CHM 1010 PGCC Barbara A. Gage

Chemical Change CHM 1010 PGCC Barbara A. Gage From Silberberg, Principles of Chemistry, 2007

CHM 1010 PGCC Barbara A. Gage Figure 1.1 A Physical change B Chemical change The distinction between physical and chemical change. (Silberberg)

CHM 1010 PGCC Barbara A. Gage Sample Problem 1.1 (Silberberg) Distinguishing Between Physical and Chemical Change PROBLEM: Decide whether each of the following process is primarily a physical or a chemical change, and explain briefly: PLAN: “Does the substance change composition or just change form?” SOLUTION: (a) Frost forms as the temperature drops on a humid winter night. (b) A cornstalk grows from a seed that is watered and fertilized. (c) Dynamite explodes to form a mixture of gases. (d) Perspiration evaporates when you relax after jogging. (e) A silver fork tarnishes slowly in air. (a) physical change(b) chemical change(c) chemical change (d) physical change(e) chemical change

CHM 1010 PGCC Barbara A. Gage

Types of Matter Element - the simplest type of substance with unique physical and chemical properties. It cannot be broken down into any simpler substances by physical or chemical means. Compound - a substance composed of two or more elements which are chemically combined. CHM 1010 PGCC Barbara A. Gage

Allowed to react chemically therefore cannot be separated by physical means. Figure 2.19 Silberberg The distinction between mixtures and compounds. S Fe Physically mixed therefore can be separated by physical means; in this case by a magnet.

CHM 1010 PGCC Barbara A. Gage

Types of Matter Atom – smallest unit of an element with all the characteristics of the element CHM 1010 PGCC Barbara A. Gage

Types of Matter CHM 1010 PGCC Barbara A. Gage Molecule - a structure that consists of two or more atoms that are chemically bound together and thus behaves as an independent unit. Figure 2.1 Silberberg

CHM 1010 PGCC Barbara A. Gage The boxes here contain submicroscopic views of particles. Indicate which box(es) contain the stated item(s) and why. a.only elements b.one compound c.mixture of compounds d.molecules a.B, C, E b.A (plus an element), D c.F d.All but E

Element Names and Symbols Number of elements – 117 (#117 has not been identified but 118 has) CHM 1010 PGCC Barbara A. Gage

Element Names and Symbols Each element has a name and 1, 2 or 3 letter abbreviation called a symbol. The first letter in a symbol MUST be capital and the other(s) lowercase. hydrogen Hhelium He carbon C cobalt Co sodium Napotassium K lead Pbmercury Hg CHM 1010 PGCC Barbara A. Gage Image from WebElements

Element Names and Symbols You must know the names and symbols of the first 38 elements on the periodic table along with Ag, Cd, Sn, I, Ba, Hg, Pb. Spelling counts! Make flashcards to help learn them. CHM 1010 PGCC Barbara A. Gage

Chemical Formulas Some elements appear in nature bonded to each other. These are referred to as diatomic or polyatomic molecules. H 2, O 2, N 2, F 2, Cl 2, Br 2, I 2 (must know) C 60, S 8, P 4 The 2 in O 2 is termed a subscript and refers to the element immediately in front of it. CHM 1010 PGCC Barbara A. Gage

Chemical Formulas CO 2 contains 1 atom of carbon and two atoms of oxygen all chemically linked. H 2 SO 4 contains 2 hydrogen, 1 sulfur, and 4 oxygen atoms. (NH 4 ) 2 C 2 O 4 - A subscript outside parentheses applies to everything within the parentheses; 2 N, 8 H, 2 C, 4 O CHM 1010 PGCC Barbara A. Gage