Anatomy of an Atom Nucleus The central part

Anatomy of an Atom Nucleus – The central part of an atom made up of Protons and Neutrons. Neutron – Particle found in the nucleus which has No Electrical Charge, and a mass about the same size as a Proton – Particle in the nucleus, which has a Positive Electrical Charge. Electron – Particle that orbits the nucleus of an atom and has a Negative Electrical Charge. They move more rapidly around the outer areas of the atom. Their arrangement determines the chemical properties of an atom.

Atoms are made up of pieces particle symbol “relative” mass “relative” charge location proton p+ 1 +1 nuclear neutron no 1 0 nuclear electron e- negligible -1 extra nuclear

“relative” vs. “absolute” particle “relative” mass “absolute” mass “relative” charge “absolute” charge p+ 1 1. 67 x 10 -24 g +1 +1. 60 x 10 -19 C no 1 1. 67 x 10 -24 g 0 0 e- negligible 9. 09 x 10 -28 g -1 -1. 60 x 10 -19 C

various atoms are arranged on The Periodic Table Over 100 various kinds of building blocks exist

Looking at an example we find all sorts of information. 6 C Atomic Number Symbol Carbon 12. 0111 Atomic Mass

Atomic number (a. k. a. proton number) • Indicates the # of p+’s an atom has • Identification Tag of the element example: each and every C atom has 6 p+’s 5 p+’s would make it B 7 p+’s would make it N

Symbol • The abbreviated shorthand used to represent a particular atom Rules Atoms are represented by a 1, 2, or in some cases 3 letter Arabic letter code. The 1 st letter is always capitalized; the others (if there any) are always expressed in the lower case.

Be careful using symbols Po PO

Atomic Mass • Indicates the amount of matter present in an atom Mass = ( # p+) + ( # no) + (# e-) But considering the negligible mass of the electron Mass = ( # + p) +(# o n)

Looking back at the original example: 6 C Carbon 12. 0111 # charge p+ 6 +6 no 6 0 e- 6 -6 18 0

Example #2 # charge p+ 47 no 61 0 e- 47 155 0 47 Ag Silver 107. 8682

Review problem #1 Fill in the chart below # 92 U Uranium 238. 0289 p+ no e- charge

Review problem #2 How many protons are in the following atom? 10 Ne Neon 20. 1797

Review problem #3 How many neutrons are in the following atom? 11 Na Sodium 22. 98977

Review problem #4 How many electrons are in the following “neutral” atom? 3 Li Lithium 6. 941