Chapter 2 Matter and Change Anything in black
Chapter 2 Matter and Change Anything in black letters = write it in your notes (‘knowts’)
2. 1 – Properties of Matter - Anything that has mass Mass - Measure of the amount of matter in an object Matter Mass We need a better definition for mass…
Mass - Measure of an object’s inertia. Inertia - Resistance to change in motion. Which of the above has more inertia? Volume - amount of space occupied by an object
mass Density = volume UNITS mass grams volume m. L density g/m. L or cm 3 or g/cm 3
The density of an object normally decreases as its temperature increases. Hot air rises!! The density of water is approx. 1 g/m. L
States of Matter Solid Particles are packed closely together; definite shape and volume
Liquid Particles are close but are free to flow past one another; shape depends on container; incompressible
Gas Particles are far apart and move freely; shape and volume depend on container; can be compressed
Physical Change A change in appearance but NOT in the chemical identity of a substance. The melting point of gallium metal is 30˚C. The figure shows how the heat from a person’s hand can melt a sample of gallium.
Phase Changes sublimate melt evaporate freeze condense deposit
The difference between a vapor & a gas A vapor is a gas that evaporates from a liquid.
The difference between evaporation & boiling Evaporation occurs only at the surface, boiling occurs throughout the liquid.
The white cloud is NOT steam. It is actually hot water vapor condensing to form a mist of water droplets
2. 2 – Mixtures Mixture - physical blend of 2 or more things Homogeneous – same composition throughout, uniformly mixed; solutions Heterogeneous – variable composition, nonuniformly mixed; contains more than 1 phase.
Olive oil Homogeneous Vinegar Homogeneous Oil & Vinegar Heterogeneous (2 phases)
Separating Mixtures Filtration – separates a solid from a liquid. Liquid that passes through the filter paper
Distillation – separates a mixture into parts based on the boiling points of each part.
2. 3 – Elements and Compounds Element – fundamental building block of matter; made of atoms. Each element has a chemical symbol. 1 st - Capital letter 2 nd - Lowercase
Compound – 2 or more atoms chemically bonded in a fixed proportion. Has a chemical formula. Compounds can be broken down into simpler substances, but elements cannot. Subscripts Chemical Formula
Chemical Change change in chemical identity; requires a chemical reaction. The layer of sugar is heated until it breaks down into solid carbon and water vapor.
The properties of compounds are different from the elements that form them. + Sodium (Na) Metal so reactive it reacts with water Chlorine (Cl 2) Toxic gas used in WWI for chemical warfare Salt (Na. Cl) Relatively harmless 2 poisonous substances react to form a completely benign compound that is necessary for us to live.
Element, Compound, or Mixture? (Figure 2. 11)
Periodic Table 7 Periods (Rows) 18 Columns (Groups or Families) Elements in each column have similar chemical properties
2. 4 – Chemical Reactions Chemical changes are also known as chemical reactions. Reactant(s) Product(s)
Possible clues that a reaction has happened 1. Transfer of Energy
Possible clues that a reaction has happened 2. Color Change
Possible clues that a reaction has happened 3. Gas Production
Possible clues that a reaction has happened 4. Precipitate Formation
Law of Conservation of Mass In any chemical reaction, reactant mass = product mass
- Slides: 30