Lesson 1: The Organization of Matter

Transcription

1 Atoms and Molecules Lesson 1: The rganization of Matter All matter regardless of its size, shape or color is made of atoms air, water, humans, dogs, shoes etc are all made up of atoms An atom is the smallest particle of matter. It cannot be divided chemically The periodic table of elements lists the names and chemical symbols that are found in nature Chemical symbols for atoms are usually composed of one capital letter (ex carbon: C) or a capital letter followed by a small letter (ex chlorine: Cl)

2 Molecules are a group of atoms that are attached by chemical bonds Visual Representations of atoms: Single atom of oxygen -- xygen gas Molecule (two oxygen atoms combines 2 ) Water molecule (an oxygen molecule attached to two hydrogen molecules 2 ) Methane molecule (one carbon attached to 4 hydrogen molecules C 4 ) C

3 Molecules are represented by their chemical formula which indicates the type of atoms and the number of each type of molecule Reading a chemical formula: Example 1: The symbol for sulfur The symbol for hydrogen 2 S This subscript number means that there are two hydrogen atoms in the molecule If there is no subscript number that means there is only 1 sulfur atom in the molecule Example 2:

4 The num the brack the numb Mg() 2 Atoms that repeat as a group are put in brackets Mg Pure Substances, Mixtures and the Particle Model of Matter Pure Substances: All matter is can be divided into two categories: Pure substances or mixtures Pure substances are made up of only one type of atom or molecule Example: Table salt is made up of only sodium chloride (NaCl) so it is a pure substance. Pure substances can also be categorized as either elements or compounds

5 An element is a substance that is made up of only one type of atoms A gold bar is made up of only gold atoms (Au) while oxygen gas is made up of only oxygen molecules ( 2 ) A compound is a substance that is formed by two or more different atoms combining table salt (NaCl) is composed of molecules containing the sodium atom (Na) and the chlorine atom (Cl) Mixtures A mixture on the other hand is a substance that contains more than one type of particle Ex. Salt water, coffee, air etc are all types of mixtures Mixtures can be classified as homogeneous or heterogeneous omogeneous (also called a solution) evenly distributed throughout ex. Tea, salt water (you see only one layer and it looks the same everywhere) A simple solution is basically two substances that are going to be combined. 1) Solute: A solute is the substance to be dissolved (sugar). 2) Solvent: The solvent is the one doing the dissolving (water). As a rule of thumb, there is usually more solvent than solute. heterogeneous unevenly distributed, will usually settle/separate into its individual parts ex. Canned tomatoes, rocks, sand and water etc (you can see more than one layer or the distinct parts) o each part of the mixture that you can make out is called a phase In some heterogeneous mixtures it is difficult to make out the different phases. These types of mixtures are called suspensions and colloids The main difference between solution, suspensions and colloids is the size of the particles that are distributed throughout the solvent Suspensions and colloids have larger particles that will eventually separate from the solvent to show two distinct phases A suspension is a mixture where the particles float in the solvent giving it an even cloudy appearance, however with time, the particles will eventually separate (either float to the top or sink to the bottom of the mixture Ex. Dirt and water or orange juice with pulp A colloid is a mixture containing small particles that are suspended as make the mixture seem homogeneous. These types of mixtures will only separate if left for a very long time. Ex. Mayonnaise, coloured paint

6 The Particle Model of Matter The particle model is used by scientists to explain the behaviour and properties of matter. The particle model is represented by the following statements: 1) All Matter is made up of tiny particles

7 2) Each pure substance is made up of one specific type of particle 3) Particles are naturally attracted to one another o Solids are more attracted and closer together, liquids are further apart and less attracted while gas particles are very far apart and weakly attracted 4) Particles are in constant motion 5) n average, particles with a higher temperature move faster than those with a lower temperature.