Download Lecture: Atomic Basics

Lecture: Atomic Basics
I. Dalton’s Atomic Theory
A. Proposed by John Dalton in 1808
B. Has 3 major parts
1. Every element is made of tiny indivisible particles called atoms.
2. Atoms of the same element are all alike.
3. Atoms of different elements can join to form molecules.
II. Atomic Structure
A. Atoms are made of three different types of particles:
Particle
Mass (atomic mass units)
Charge
Location
proton
1
+1
nucleus
neutron
1
0
nucleus
electron
0
-1
outside nucleus
B. Atoms are electrically neutral; they are made up of charged particles, but the atom is neutral.
1. An atom has the same number of protons and electrons.
2. An atom with 6 protons and 6 electrons has a total charge of zero.
a. 6 positive protons + 6 negative electrons = 0
(+6)
+
(-6)
=0
III. Atomic Differences
A. Protons
1. Atoms of different elements have different numbers of protons.
a. ALL atoms of lithium have 3 protons
b. ALL atoms of bismuth have 83 protons
c. ALL atoms of calcium have 20 protons
2. The number of protons in an atom is called the atomic number (Z)
a. Z = # protons
= # electrons
B. Atomic Mass Number
1. Atoms of the same element that have different numbers of neutrons are called isotopes.
2. The total number of particles in the nucleus is called the atomic mass number (A)
a. A = total number of particles in the nucleus
= # protons + # neutrons
=A
3. Elemental Notation
4. Calculating the number of neutrons in an atom
a. # neutrons = mass number – atomic number
5. Let’s do an example
a. Neon has A = 20, Z = 10
b. Silver has A = 108, Z = 47
# particles in nucleus
# protons
# neutrons
# electrons