A TOMIC S TRUCTURE What atoms look like

W HAT ARE ATOMS ? An atom is the smallest part of matter that can exist. Atoms are microscopic particles. That means we can’t see them! You can fit about 500,000 atoms behind a single strand of human hair Atoms are always moving. How small is an atom?

W HAT ARE ATOMS ? Atoms are made up of 3 main parts: Protons Neutrons Electrons

S TRUCTURE OF THE A TOM

P ARTS OF THE ATOM Nucleus - the small center of an atom So tiny that it is 1/100,000 the size of the entire atom! Contains most of the atoms mass Inside the nucleus: Protons- have a positive charge (+) Atoms are identified by the number of protons in its nucleus # of protons in an atom = atomic number Neutrons- have no charge (0) Protons and neutrons are the same size

P ARTS OF THE ATOM Outside of the nucleus are electron clouds (rings around the nucleus) with even smaller particles! Electrons - have a negative charge (-) Are much smaller than protons and neutrons There are the same number of protons and electrons in an atom!

P ARTICLE SUMMARY ParticleMass?ChargeLocation ProtonA lotPositive (+) Inside the nucleus NeutronA lot (same as protons) No charge (0) Inside the nucleus ElectronA littleNegative (-) Outside the nucleus in electron clouds

E LEMENTS Remember: The number of protons in an atom’s nucleus determines what the atom is… Atoms help create the…. Elements Made up of only 1 kind of atom (pure substance) Atoms in an element all have the same number of protons Atoms in an element all share the same physical and chemical properties An atom with 6 protons is a carbon atom- carbon is an element

E LEMENTS There are over 100 different elements in the world 92 of these are found in the earth Which elements do you know? Silver Aluminum Gold Carbon Copper Helium Iron

H OW TO FIND OUT INFORMATION ABOUT AN ELEMENT : Each square on the periodic table includes lots of information about an element:

H OW TO FIND OUT INFORMATION ABOUT AN ELEMENT Name: tells us what element it is Symbol : the 1 or 2 letter abbreviation that represents the elements name Located in the center of the square Atomic Number: the number of protons in an element Located above the symbol Atomic Mass: the number of protons + the number of neutrons in an element Located below the symbol Bigger number

H OW TO FIND OUT INFORMATION ABOUT ELEMENTS How do you know how many protons, electrons and neutrons are in each element? Number of protons = number of electrons Number of protons = Atomic Number Number of electrons = Atomic Number Number of neutrons = Atomic mass - Atomic Number

Y OU TRY ! Element: Nitrogen Symbol : N Atomic Number : 7 Atomic Mass : 14 Number of Protons : 7 Number of Electrons : 7 Number of Neutrons : 7 N Nitrogen

M OLECULES Molecules are formed when 2 or more atoms join together Can be the same kind of element O2 (air) 2 atoms of oxygen Or they can be different kinds of elements H2O (water) 2 atoms of hydrogen and 1 atom of oxygen

A TOMS VS MOLECULES AtomsMolecules Single (1 type)Couples or groups (more than 1 atom joined together)