Before chemistry there was….. Alchemy
Alchemy:A medieval science and philosophy aiming to achieve: 1. Transmutation of base metals (like lead) into gold
Alchemy 2. Discovery of a universal cure for disease
Alchemy 3. Discovery of a way to prolong life
Has modern science achieved these things? Wealth for all? Cure for disease? Prolonged life?
Why is Gold valuable? • Rare • Pretty • Soft, easy to shape • Resists corrosion • Chemically unreactive
Modern Chemistry The science that studies the structure, composition, and properties of substances and their transformations (Webster)
What are the simplest substances? • The ELEMENTS ( only about 90 occur naturally, 114 discovered) • Listed in the Periodical Table • Basic building blocks for all other more complex substances (compounds) found in the universe
Abundance of common elements in the Universe • 60% Hydrogen H element #1 • 37% Helium He element #2 • 3% elements # 3-90
Abundance of elements on Earth (crust and atmosphere) • 35% iron • 30 % oxygen • 15 % silicon • 13% Magnesium • 2.4% nickel • 4.6% others
Origin of the Elements Big Bang!
Big Bang • 15-20 billion years ago • Matter and energy scatter, expand, and cool • Matter condenses to form galaxies, Element Hydrogen forms • Stars form in galaxies. In stars, H fuses to form Helium and energy • More fusion allows heavier elements to form
Matter Anything that has mass and takes up space (volume) What is NOT matter???
Matter Can it be separated by physical means? If yes….
Physical ways to separate a mixture • Filtering (particle size) • Distillation (boiling point) (dissolved solid)
Physical ways to separate a mixture • Chromatography (attraction to paper)
Is the mixture uniform throughout? • IF yes, it is HOMOGENEOUS
YES NO YES NO
If matter can NOT be separated by physical means…. It is a SUBSTANCE If the substance can’t be broken down, it is an ELEMENT Elements are made of only one type of atom Ex. Aluminum, carbon, oxygen
SUBSTANCE If the substance CAN be broken down, it is a COMPOUND, made of two or more different kinds of atoms chemically bonded together. Ex. Water (2 Hydrogens and 1 oxygen)
YES NO YES NO Yes NO
ELEMENTS can be…. • MONATOMIC : single atoms Al • DIATOMIC : two of the same atom bonded together in pairs O2 • POLYATOMIC: three or more of the same atom bonded together O3
Review What is…… MATTER SUBSTANCE MIXTURE ELEMENT COMPOUND HETEROGENEOUS VS. HOMOGENEOUS
CHEMISTRY: THE STUDY OF MATTER Did you know that…….. One of the most popular “foods” in the United States is an entirely SYNTHETIC (man-made) mixture. Can you guess what it is?
SODA The average person consumes 40 GALLONS (!) of soda each year Mixture: carbonated water sweetener, acids, flavorings, caffeine
States of Matter GAS LIQUID SOLID
Physical Properties of Matter The properties of a substance that can be demonstrated without changing the composition of the substance Size (length, volume) Density Mass Color
Physical Properties Melting Point Ex. Ice (solid water) starts to melt to liquid water at 0 degrees Celsius Boiling Point Ex. Water boils into steam at 100 degrees Celsius
Physical Properties Malleability: can be pounded into a new shape without breaking Metals are malleable
Physical Properties Iron is malleable Fe
Physical Properties Ductility Can be pulled into long wires without breaking Metals are ductile
Physical Properties Crystal Shape Reflects the regular arrangement of atoms in the solid
Physical Change A change in the sample of matter that does not result in a NEW substance: Phase Changes Changes in shape Solid liquid gas
Chemical Properties of Matter How matter behaves when it changes into a NEW substance. EX. Iron rusts silver tarnishes Milk sours sugar ferments eggs rot leaves turn paper burns
Chemical Change Substance changes into a NEW substance. This change is often an irreversible and permanent change in composition