Matter Unit Section 1 I) Matter A.) Def: anything that … 1. Has MASS 2. Takes up space. B.) Almost everything around us is matter. Ex – air, table, chair, us, water, etc. Ex. NOT MATTER – heat, light. C.) If almost everything is matter, why doesn’t everything look the same? II.) Atoms A) Def: tiny particles that are the BUILDING BLOCKS of matter. B) How they are arranged- why everything looks different. C) Properties of matter determined by 1. Types of atoms (see next slide) 2. How they attach to each other C.) 3 basic particles of an atom 1) Neutrons • • Have a NEUTRAL charge Exist in the NUCLEUS (center/middle of atom) 2) Protons • • Have a POSITIVE charge Exist in the NUCLEUS too! C.) Parts of Atom cont. 3) Electrons * Have a NEGATIVE CHARGE * Exist OUTSIDE the nucleus * Kind of like orbits – in an “electron cloud” *Different energy depending on how close to the nucleus. (Think of a BEE HIVE) < Lower Energy – closer to nucleus. <Higher Energy – farther away from nucleus. III) What does an atom look like? IV.) Elements A.) Def: substances that ~ 1.) Are made up of only one type of atom. 2) Cannot be broken down into any simpler substances by normal physical or chemical means. 3) Periodic Table of Elements *Familiarize yourself w/ it *Know what those numbers mean! V) What those “numbers mean” (Periodic Table) A) ATOMIC NUMBER = Number of PROTONS * All atoms of the same element have the same number of PROTONS *Found above the element symbol on the periodic table. What is Helium’s atomic number? How many protons does Helium have? V) What those “numbers mean” (Periodic Table) CONT. • B) How many Electrons? 1) In a NEUTRAL atom … Atomic No. = No. of Protons = No. of Electrons 2) Atoms can lose or gain electrons – no longer neutral = ION (charged atom) - More protons than electrons = Positively charged ion. - More electrons than protons = Negatively charged ion. V) What those “numbers mean” (Periodic Table) CONT. C) How many neutrons? 1) Atomic Mass (or Mass Number) (round – don’t use decimals) = # of Protons + # of Neutrons 2) Can have different number of Neutrons – called an ISOTOPE of an element. *Scientist uses of isotopes: - radioactive isotopes to fight cancer - helps determine age of rocks VI) Practice – parts of atom • Worksheet. VII. Bohr’s Diagram • One dimensional view of an atom. • Center = nucleus w/ protons & neutrons • Outer Shells = layered areas of electron cloud – 1st = holds 2 – 2nd = holds 8 – 3rd = holds 18 • Why important? SHOWS how likely atom will BOND w/ another atom. • Electrons in outer shell are called VALENCE electrons. Draw one …