Chap 1 Matter and Change Honors Chemistry

1.0:Chemistry Chemistry – the study of the composition of substances and the changes they undergo Five major divisions: Organic – carbon compounds Inorganic – substances without carbon Analytical – composition of substances Physical – theories and experiments describing behavior of chemicals Biochemistry

1.1:Properties of Matter Substance Physical property Chemical property States of matter Solid Liquid Gas Vapor

Substances Matter is anything that has mass and volume Matter that is always the same is a pure substance Water, H 2 0, is a pure substance but well water is not because it may have different levels of salts and minerals in it

Physical Properties A characteristic of a substance that can be observed without changing the substance is a physical property. Density, color, melting point, and boiling points are all physical properties

Extensive and Intensive Properties Properties that are dependent on the amount of a substance present are extensive properties Mass, length, and volume are all extensive Properties that are not dependent on the amount of a substance present are intensive properties Density, melting points and boiling points are all intensive

Chemical Properties The ability of a substance to change from one type of substance into another is a chemical property Iron reacting with oxygen in the air to form iron oxide, or rust, is a chemical property Water freezing is a physical property since it is still water, just in a different form

States of Matter Solids generally have atoms that are close together and are held in position by strong attraction Solids have a definite shape and a definite volume Solids are difficult to compress since their atoms are already so close together

States of Matter... Liquids are made of atoms that are somewhat attracted to each other and are able to move around Liquids have a definite volume but not a definite shape Since liquids are free to move they cannot be compressed

States of Matter... Gases are not dense as they are made of quickly moving atoms that are widely spaced apart and have little to no attraction to each other Since the atoms of a gas are so far apart, gases can be compressed A vapor is used to describe substances in the gaseous form that are not gas at room temperature i.e. water vapor but carbon dioxide gas

1.2: Changes in Matter Physical change Chemical change Law of conservation of mass

Physical and Chemical Changes Physical changes do not change the type of substance Bending, melting, grinding and crushing are all examples of physical changes Chemical changes do change the type of sustance Milk spoiling, leaves rotting, iron rusting are all examples of chemical changes

Conservation Of Mass The first law of thermodynamics states that matter and energy cannot be created or destroyed. As a result, every chemical change must obey the law of conservation of mass; the mass of the reactants must equal the mass of the products Antoine Lavoisier, known as the father of chemistry, was the first to document this observation

Father of Chemistry??

1.3: Mixtures of Matter Mixture Heterogeneous mixture Homogeneous mixture Solution Filtration Distillation Crystallization Chromatography

Mixtures A mixture is a combination of two or more substances that are not chemically combined Mixtures can be heterogeneous (different throughout) or homogeneous (same throughout) Homogeneous solutions are also called solutions Solutions do NOT have to be liquid An alloy is a homogeneous mixture of metals An example is steel

Separating Mixtures Mixtures can be separated into their parts by a variety of methods. Filtration separates liquid and solid mixtures using a porous barrier Distillation separates liquid mixtures based on differences in boiling points Crystallization involves solid particles forming out of solution Chromatography separates pigments based on differences in solubilities

1.4: Elements and Compounds Element Periodic table Compound Law of definite proportions Percent by mass Law of multiple proportions

Elements All matter is made of atoms There are about 100 different types of atoms that we know of. These are the elements Elements are pure substances that cannot be broken down by normal chemical means Each element has its own one, two, or three letter symbol. The first letter in the symbol is always capitalized.

Periodic Table The periodic table is a list of all the known elements The specific placement and arrangement of the elements on the periodic table tells you a lot about the element Rows on the periodic table are called periods and columns are called groups or families Elements in the same group share chemical properties

Periodic Table....

Compounds A combination of two or more elements in a specific ratio is a compound Compounds are not mixtures because the elements are chemically combined Chemical formulas are a combination of symbols and subscripts, numbers listed after and below the symbol, detailing the ratio between the elements in the compound For example, H 2 0, is made of two hydrogen atoms and one oxygen atom

Compounds... Compounds can be separated into their elements by chemical means. In other words, a reaction must take place to break a compound apart. Compounds are often more stable than atoms alone. As a result, energy is often needed to separate a compound into its elements. The chemical properties of compounds are different than the properties of the elements that make the compound For example, NaCl is made from sodium, a metal that reacts explosively with water, and chlorine, a poisonous gas. Yet NaCl, table salt, is tasty on french fries!

Law of Definite Proportions Regardless of the amount of the compound present, the ratio of the elements that compose the compound are always the same. This is the law of definite proportions Each sample of a compound displays the same percent by mass of each element Percent by mass = mass of the element__ x100% a mass of the compound

Law of Multiple Proportions Some elements combine in different ways to make a variety of compounds. For example, hydrogen and oxygen combine to form water, H 2 0, but also hydrogen peroxide, H The law of multiple proportions states that when different compounds are formed from the same elements, each compound has its own distinctive ratio of elements