What is Matter? • Must have mass • Occupies space (has volume)
Density • Because all matter has mass and volume, all matter has density. D = M V
Law of Conservation of Matter • Matter cannot be created or destroyed
When 400 grams of wood are burned only about 30 grams of ash remain. • What happened to the missing matter?
States of Matter • Matter can exist in three basic states: • Solid (s) • Liquid (l) • Gas (g)
A Fourth State of Matter? • Plasma • Occurs when the atoms of matter have been stripped of their electrons.
Elements • Made up of atoms of one specific type • Cannot be broken down further by a chemical reaction • Have specific physical and chemical properties.
The Periodic Table of Elements • Each element has its own atomic number • Atomic number tells us the number of protons in that elements nucleus.
Where Do We Get Elements? • Obtained in nature in their pure state.
Some elements are combined together in compounds and are separated out through chemical reactions.
Some elements don’t exist naturally, and are man-made through nuclear bombardment reactions
Elements and Their Symbols • Elements have either one or two letters when they are written as a symbol. • If two letters, the second letter is written lower case. (Ex: Write Cu for copper not CU)
Usually it is pretty easy to match an element to its symbol (Ex: Neon = Ne) • Sometimes the symbol is derived from a Latin name for the element. • Ex: Au = gold (comes from Latin word aurum)
Here are some of the harder elements to match their name to their symbol. Na = sodium K = potassium Fe = iron Cu = copper Sb = antimony Sn = tin Pb = lead Hg = mercury W = tungstun Au = gold Ag = silver Tricky Elements
Phases and Elements • Under standard conditions, most elements exist as solids. • The Gases: • H, He, Ne, Ar, Kr, Xe, Rn, O, F, Cl • The Liquids: • Hg, Br
Diatomic Elements • Two atoms of the same element joined • Bromine, Iodine, Nitrogen, Chlorine, Hydrogen, Oxygen, Fluorine • BrINClHOF
Compounds • Most elements in nature do not exist in their pure state, but in compounds. Compound = Two or more different elements bonded together chemically Ex: C6H12O6, MgCl2, CH4, NO2, CO2, NaCl
Law of Definite Proportions • Elements in compounds have definite fixed proportions by mass.
Getting New Properties • Compounds have different chemical and physical properties than the elements that make them up.
- Sodium (Na) Toxic, reactive metal that will explode in water - Chlorine (Cl) Brown toxic gas that was used as a chemical weapon to kill people in WWI Sodium Chloride (NaCl) White edible crystal, and salt for my french fries!!
Focus Question • What are the differences between elements and compounds?
Mixtures • Two or more pure substances physically mixed together. • Can be two or more elements, compounds or both. • Mixtures can be solid, liquid or gaseous.
Composition Not Fixed • The composition of a mixture is NOT FIXED. • It can vary depending on how much of each component is added.
Retaining Their Properties • The substances in mixtures retain their own individual properties. • Ex: Iron filings (Fe) and sand (SiO2) • Even if mixed the iron retains its magnetic properties
Homogeneous Mixtures • Components are distributed uniformly at the molecular level. • All true solutions are homogeneous.
Aqueous = (aq) Mean the substance is dissolved in water. • Ex: NaCl (aq) means a salt water solution
Heterogeneous Mixtures • Components are not uniformly distributed at the molecular level. • Colloids and suspensions are included in this category.
How to Tell if a True Solution • Tyndall Effect • When you have a suspension or a colloid the larger particles will scatter a beam of light. In a true solution the light will not be scattered
Separating Mixtures • Components of a mixture retain their own original properties, you can use these properties to separate the components. • Ex: density, particle size differences, solubility differences, boiling point temperature, magnetic properties
Filtration • Ex: Separate water and sand • Technique cannot be used to separate components of solutions
Separatory Funnel • Ex: Separate oil and water
Evaporation • Ex: Separate sugar from water
Chromatography • Separates different compounds dissolved in the same liquid. • Use Chromatography Paper • Liquid runs up the paper and components separate out along the length of the paper. • Ex: Separate different types of chlorophyll