Matter
Origins of the Idea Democritus (~400 BCE) Matter is composed of atoms Atoms are eternal, invisible, indivisible, and incompressible Greeks believed in 3 phases or states of matter Solid, liquid, gas We now add plasma as the fourth phase
Matter in the Universe 99% of the known matter in the universe is Hydrogen and Helium The majority of the known matter is in the form of a plasma in stellar interiors The average density of the known matter in the universe is such that 1 gram would occupy a volume 30 x that of Earth The location and characteristics of most of the matter in the universe is unknown – dark matter
Antimatter A matter particle and an antimatter particle are the same with the exception of charge and magnetic properties (which are opposite). Naturally formed and man-made. When matter and antimatter particles collide, they annihilate each other.
Elements Fundamental forms of matter Can’t be broken apart by normal means 92 occur naturally on Earth They are the same everywhere
What Are Atoms? Smallest particles that retain the distinguishing physical and chemical properties of an element Made up of subatomic particles: Protons (+) Electrons (-) Neutrons (no charge)
Examples of Atoms electron proton neutron Hydrogen Helium
Atomic Number Number of protons All atoms of an element have the same atomic number Atomic number of hydrogen = 1 Atomic number of carbon = 6
Isotopes vary in mass number Number of protons + Number of neutrons Isotopes vary in mass number
Isotopes Atoms of an element with different numbers of neutrons (different mass numbers) Carbon 12 has 6 protons, 6 neutrons Carbon 14 has 6 protons, 8 neutrons
Chemical Bonds, Molecules, & Compounds Bond is union between electron structures of atoms Atoms bond to form molecules Molecules may contain atoms of only one element - O2 Molecules of compounds contain more than one element - H2O
Chemical Origins Most chemical elements were created after the Big Bang in subsequent generations of stars. Nucleosynthesis: primordial (H, He, Li) stellar (He -> Fe) explosive (Co -> …)
Chemical Origins H and He are and were the most abundant. Today many elements are abundant; C, N, H and O are fundamental to organic (carbon-bearing) life.
Abundances of the Elements