Chapter 1 The Science of Chemistry
1-1What is Chemistry
Objectives: A. Know the characteristics of solids-liquids-gases.
1. Solids have a fixed volume and definite shape. Particles are held together by strong intermolecular forces and vibrate in fixed positions.
2. Liquids have a fixed volume and assume the shape of their container. Particles are not held in position by strong forces, but slip and slide past each other and thus at high speeds.
3. Gases have neither fixed volume nor fixed shape and assume the shape of their container. Particles are weakly attracted to each other and move independently
B. Describe both physical and chemical changes and be able to give examples of each
Physical Change- changes in which the identity of a substance doesn’t change. The particle arrangement and speed can change (melting, boiling, dissolving, crushing, etc)
Chemical Change- the identity of the substance changesand a new substance w/ new properties has been formed.
C. Identify reactants and products in a chemical reaction
Reactants Products (mass of reactants = mass of products)
D. List four observations that suggest a chemical change has occurred
1. Evolution of gas
2. Formation of a precipitate (solid from two clear liquids0
3. Release or absorption of energy (change in temperature or giving off light)
4. Color change
1-2Describing Matter
Objectives: A. Distinguish between mass-weight-volume-matter
Matter- anything that has mass and volume
Volume-space an object occupies
Mass- quantity of matter (Balance is used to measure mass)
Weight- depends on gravitational pull on matter (Scale is used to measure weight)
B. SI units-identify and use in calculations
Mass (grams) Volume (mL) Length (m) Time (s) Amount of substance (n- mole) Temperature (K- kelvin)
C. Conversion factors- unit cancellation
Know SI PrefixesKilo (k)
Hecto (h)
Deka (da)
Base (m, L, g, s, n, etc)
Deci (d)
Centi (c)
Milli (m)
Derived units 1000 mL = 1000 cm3 = 1 L = 1 dm3
D. Physical properties- Physical property- (MP, BP, density, solubility, color, hardness, density) depends on the nature of the material
Density= mass (g)/volume (mL) How tightly packed the particles of matter are (dependant on temperature) Density of water at 25C = 1.0 g/mL
Density can be used to identify and unknown substance
E. Chemical properties-Chemical property (flammability, reactivity, rusting) depends on the ability of the substance to undergo change
1-3 How is Matter Classified?
Objectives: A Distinguish between elements & compounds
Compounds- two or more elements chemically combined CO2
Formula –expresses a compound
Symbol-expresses an element
Elements- composed of the same type of atoms (periodic table) can not
be broken down into simpler substance
B. Distinguish between pure substance and mixtures
Molecules (pure substance) Diatomic molecules N2, O2, F2, Cl2, Br2 I2,
At2, H2
Allotropes-different forms of the same element O2 O3 ozone
Mixtures- two or more substances mixed together that retain their own
properties and thus can be separated- not chemically combined (air,
alloys (different metals in a
mixture) 24 karat gold (pure gold) 18 karat 18g gold 6g of Ag & Zn
C. Classify mixtures as homogeneous or heterogeneous
Homogeneous-particles evenly distributed throughout material
Heterogeneous-not evenly distributed throughout material or it can
settle out w/ time like paint
D. Difference between mixtures and compounds
Matter
↓
Heterogeneous (contains two or ← → Homogeneous (contains one phase)
more phases) ↓
Solution (Homogeneous ← → Substance (Pure)
Mixture) ↓
- Solute Compounds
- Solvent ↓ Elements
- Molarity (concentration of ↓
a solution)(M) Atoms