Matter Chapter 2.1

Matter Anything that has mass and occupies space. Chemistry is the study of matter and how it changes.

Pure Substances Uniform and definite composition Formed and separated chemically 2 types Elements & compounds

Pure Substance Elements – a substance that cannot be broken down into smaller substances. Atoms – smallest particle that has properties of an element. Both expressed by symbols

Compounds Compounds – a substance formed when two or more elements chemically combine together.

Molecules The smallest unit of a substance that exhibits all of the properties characteristic of that substance (compound). Two or more atoms chemically combined

Chemical Formulas Ex. C16H10N2O2

Mixtures A physical combination of more than one substance. (Two Types)

Homogeneous Mixtures Solutions Same throughout (miscible) ex: flat soda, salt water, black coffee

Heterogeneous Mixtures Not uniformly mixed, different parts Substances that need to be shaken ex: noodle soup, granite

Classifying Liquid Mixtures: miscible-dissolve into each other immiscible-don’t mix into each other. You can see layers ex: oil and water.

Liquids Mix with Gas Can you think of a very common example???

Matter and Energy 2.2

Kinetic Theory All matter is made of atoms and molecules that act like tiny particles.

Kinetic Theory 2.These tiny particles are always in motion. The higher the temperature, the faster the particles move.

Kinetic Theory 3. At the same temperature, heavier particles move slower than lighter particles.

Phases/States of Matter Gas liquid solid plasma

States of Matter - Gases no definite shape. no definite volume. easy to compress. most random arrangement of particles. Most spread out.

Gases Property of gases is called pressure. the force exerted per unit area of a surface

Liquids Definite volume no definite shape (takes shape of container) Difficult to compress disorderly arrangement on particles Close together

Liquids Property of Liquids is called viscosity. the resistance of a fluid to flow

Solids Definite shape Definite volume Difficult to compress Orderly arrangement of particles close together Smallest amount of movement of particles.

Energy The ability to change state or move matter. Changing state does not change composition of the substance

Changes of State solid liquid gas

Law of conservation of matter (mass) Matter (mass) cannot be created or destroyed. It only changes its state or rearranges its atoms.

Law of conservation of energy Energy cannot be created or destroyed. It converts from one form to another during chemical or physical changes.

Properties of Matter 2.3

Physical Property A characteristic of a substance that can be observed or measured without changing the composition of the substance.

Physical Property Melting and freezing points. Solubility Dissolving of a solid into a liquid. Density

Why do some things float while others sink?

Density mass/volume (D=m/V) UNITS: mass – (g) Volume – (mL) or (cm3) density – (g/mL) or (g/cm3)

Density Buoyancy- The force with which a more dense fluid pushes a less dense substance upward. ex. floating ice.

Example An unknown metal is measured to be 36 grams. What is it’s density if it has a volume of 15.5 cm3? D=m/v d= 36 g/ 15.5 cm3 D = 2.322 g/cm3 Last point is sig. figs. 2.3 g/cm3 +1 +1 +1 +1 +1

Chemical Properties The way a substance reacts with others to form new substances with different properties.

Chemical Properties Flamability Reactivity corrosion

                                                                           

Physical Changes A change in the physical form or properties of a substance that occurs without a change in composition.

Chemical Change A change that occurs when a substance changes composition by forming one or more new substances.

Chemical Change 4 signs: Evolution heat or light Color change Formation of gas Formation of a precipitate (solid residue)