WELCOME TO CHEMISTRY!
WHAT IS CHEMISTRY? • Chemistry is the study of matter and the changes that it undergoes.
WHAT IS MATTER? • Matter is anything that has mass and volume. • Mass refers to the measure of the amount of material in an object ( measures the resistance to an object being moved). • Volume refers to the amount of space an object occupies.
MATTER HAS 4 STATES • Solid • Liquid • Gas • Plasma
SOLIDS • State of matter in which the particles are closely packed. • Solids have definite shape and definite volume • Solids essentially cannot be compressed.
LIQUIDS • Particles are arranged so they can slide past one another. • Liquids take the shape of their container and have definite volume. • Liquids essentially cannot be compressed.
GASES • Particles are spread out widely. • Gases have neither definite shape nor definite volume. • Are very compressible.
PLASMA • An electrically neutral gas of ions (charged particles) and electrons (negatively charged particles)…VERY HIGH ENERGY!! Thought to be found in stars. • Is present when nuclear fusion occurs..requires a temp of 100,000,000 0C.
The smallest unit of matter is the atom • are the smallest unit of matter capable of existing by themselves. • 2 or more atoms chemically bonded together are referred to as a molecule.
MODELS OF THE ATOM orbits
Atoms are composed of the following subatomic particles. • Protons- Positively charged particles located in the nucleus of the atom. • Neutrons- Non-charged nuclear particles located in the nucleus of the atom. • Electrons- Negatively charged particles that move around the nucleus located in the electron cloud
Matter with only one type of atom are called elements. • Each element has a unique number of protons in the nucleus of its atoms. This is what defines that particular element.
ELEMENTS (CONT). • Chemists use elemental symbols as a shorthand way of representing elements. • These symbols consist of 1, 2, or 3 letters (only the 1st is uppercase). • Many elemental symbols show the Latin origin of the element’s name.
Periodic Table of Elements • 114 elements • Vertical column = groups • Horizontal rows = periods • Traits are organized by similar properties
ALL MATTER CAN BE CLASSIFIED AS EITHER A SUBSTANCE OR A MIXTURE • A substance is matter that has a fixed composition and distinct properties. • A mixture is a combination of 2 or more substances, each of which retains it’s properties.
Substances can be either elements or compounds. • An element is a substance in which all atoms have the same number of protons. • Elements cannot be decomposed into simpler substances.
Compounds • Compounds are substances in which 2 or more elements chemically combine to form a new substance with new properties. • Compounds can be decomposedinto simpler substances.
COMPOUNDS CAN BE CHEMICALLY BROKEN DOWN • This can be accomplished through the use of heat energy (thermal decomposition) or electric current (electrolysis).
EVERY SUBSTANCE HAS A UNIQUE SET OF PROPERTIES • Properties are characteristics that allow us to recognize and distinguish a substance from other substances.
PHYSICAL PROPERTIES • Physical properties are properties that can be observed or measured without changing the identity and composition of the matter. • Physical properties include color, odor, density, melting pt., boiling pt., malleability, ductility, hardness, etc.
CHEMICAL PROPERTIES • Chemical properties describe the way a substance may change or react to form other substances. • To observe this property you must carry out a chemical change. • An example would be burning in the presence of oxygen.
MATTER UNDERGOES CHANGE • This may be physical change or chemical change.
PHYSICAL CHANGES • In physical changes, the substance changes its physical appearance but not its composition. • An example would be changing states. • Evaporation of water into water vapor
CHEMICAL CHANGES • In a chemical change, a substance is changed into 1 or more new substances with new properties. • Chemical change involves rearrangement of atoms. • Aluminum rusting, fireworks exploding
INTENSIVE PROPERTIES • Are independent of sample size. • Examples include density, temperature, melting point, etc. (1 gal of water or 1 cup of water: both have same boil point.) • Can be used to identify a substance.
EXTENSIVE PROPERTIES • Are properties that depend on sample size. • Examples include mass, volume, and length • 1 gal of water will have a greater mass than 1 cup of water.
Mixtures can be either homogeneous or heterogeneous. • Homogeneous mixtures are uniform (have the same composition) throughout. Homogeneous mixtures are also called solutions. Ex: salt, air, water • Heterogeneous mixtures are non-uniform throughout. Ex: sand, wood, rock
MIXTURES CAN BE PHYSICALLY SEPARATED • Filtration • Distillation • Chromatography
FILTRATION • In filtration, the mixture is separated based on differences in particle size.
DISTILLATION • Distillation separates components based on differences in boiling point.
CHROMATOGRAPHY • Separates mixture components based on differences in attraction to a surface.
SCIENTIFIC DATA FALLS INTO 2 CATEGORIES • Qualitative data • Quantitative data
Qualitative • Qualitative data consists of descriptiveterms. There is no use of numbers. • Determines the presence or absence of a particular substance in a mix. • Ex: water is a liquid
Quantitative • Quantitative data consists of measurements (numbers) • Determines the amount of substance that is in a sample. • Water has a boiling point of 100degrees Celsius
Scientific Method • Hypothesis : possible explanation of an observation. • Theory: set of tested hypothesis that give an explanation of a natural phenomena • Law: concise statement or explanation
Apples, Volkswagens, Pigeons or Metric? UNITS ARE EVERYTHING! Chemistry is in the details. The slightest change or mistake can mean a world of difference. This IS going to drive you nuts this year, and you will hate chemistry, me, and the universe, but we go’tta do it!
MEASUREMENT • At one time measurement was inconsistent and therefore, unreliable. • Scientists need to be able to repeat each other’s experiments to verify/modify scientific knowledge. • To assist in this process, all scientist use the SI system of measurement. (AKA your new best friend!)
Base Units mass gram g length meter m time seconds s electric current ampere A temperature Kelvin K light intensity candela cd amt. Subst. mole mol l
MEASUREMENT (CONT) • Scientist often use prefixes in conjunction with the basic unit of measure. • The indicate decimal fractions or multiples of various units. • Ex: milli = 10-3 1 milligram = 1 mg = 10 -3 grams
MEASUREMENT (CONT) PrefixSymbol Exp. Represent. Giga G 109 mega- M 106 kilo- k 103 hecto- h 102 deka- da 101 deci- d 10-1 centi- c 10-2 milli- m 10-3 micro- µ 10-6 nano- n 10-9 pico- p 10-12 MEMORIZE THIS TABLE !!!! ROYO pg 17 table 1.3