What is Chemistry?

Learning Objectives  What is chemistry?  What are the building blocks of matter?  How does matter interact?  How is matter organized?

What is Chemistry?  The study of the composition of matter and the changes that matter undergoes  It affects all aspects of life and non-living objects too  Chemistry explains things that we observe in the world around us  For example: the changing of the leaves in fall

Matter  Is anything that has mass and occupies space  It doesn’t have to be visible  For example: humans, air, water, your table & plants  What isn’t matter?  Light, heat, sound, electricity & gravity

Phases of Matter  Three main phases:  Solid  Liquid  Gas  What is the 4 th state of matter and where is it found?

Elements  Are the simplest form of matter  114 elements have been identified  Different elements combine to form compounds

The Periodic Table

Periodic Table Periodic Table

Atom  Is the simplest particle of an element that retains all the properties of that element  They are too small to observe directly  So we use a model

Atom Model

The Nucleus  Located in the middle of an atom  Made up of 2 subatomic particles: Protons-have a positive charge Neutrons-have no charge

Atomic Number, Atomic Mass,& Mass Number  The number of protons in an atom determines the atomic number of the element  The atomic mass is the average mass of the atoms in the element  The mass number an atom is the total number of protons & neutrons

Electrons  Balance out the number of protons with negative charges  They are very high energy and have very little mass  They are found in orbitals around the nucleus  The farther away from the nucleus, the more energy an electron has

Compounds  A compound is a substance made of two or more different elements that are chemically bonded  Compounds are unique  A chemical formula shows the kinds and proportions of atoms of each element in the compound  For example: Fe 2 O 3  2 iron atoms and 3 oxygen atoms

How many of each?  C 8 H 10 N 4 O 2 C3H8OC3H8O  KMnO 4  CaCl 2 H2OH2O  NaCl

Molecules  A molecule: is the simplest part of a substance that retains all of the properties of the substance and can exist in a free site  Some molecules are composed of atoms of different elements  Some molecules are composed of atoms of the same element

Diatomic Molecules  Are molecules composed of atoms of the same element  Examples: Hydrogen, Iodine, Bromine, Oxygen, Nitrogen, Chlorine, & Fluorine  HI BrONClF

Pure Substances & Mixtures  Pure Substance: is matter that has a fixed composition and definite properties Examples: Elements & Compounds  Mixture: is a combination of 2 or more substances that are NOT chemically combined Examples: Air & Grape Juice

Mixtures  Can be separated  They are formed by mixing pure substances  They have properties similar to the pure substances that make them up  Mixtures are classified by how well they are mixed

Types of Mixtures  Heterogeneous: substances in which components are NOT distributed evenly  Examples: flour & water, sand & salt  Homogeneous: substances in which the components are evenly distributed  Examples: Pop, sugar & water  Miscible: A homogeneous mixture of liquids  Example: Gasoline  Immiscible: A heterogeneous mixture of liquids  Example: Oil & Water