Wake-up
a. Refer to element below. Name the element.b. How many protons, neutrons, and
electrons?c. Naturally occurring Europium consists of
two isotopes with a mass of 160 and 161. If Eu-160 has abundance 49% and Eu-161 has 145%. What is the average atomic mass of Eu?
Electron Configuration … Where are electrons found?
Electrons are important…Because they feel each other first when atoms meet
.
Outer electrons of atoms interact with other electrons first!
Neils Bohr: 1913• Electrons move in orbitals around nucleus• AKA Planetary Model• Each orbital holds a certain number of electrons
with increasing energy
Electron Energy Levels1st Energy Level (surrounding the nucleus) contains
2 electrons
2 electrons
Electron Energy Levels2nd Energy Level (surrounding the nucleus)
contains 8 electrons
8 electrons
Electron Energy Levels3rd Energy Level (surrounding the nucleus)
contains 18 electrons• BUT if not enough to fill 18 and enough to fill 8,
fill 8 and move to next energy level.
18 electrons (8e-)
Electron Energy Levels4th Energy Level (surrounding the nucleus)
contains 32 electrons
32 electrons
How to Complete a Bohr Ring ModelFind the number of electrons; start filling the
energy levels starting with the 1st and working way out
Example #1: SodiumHow many electrons does Sodium have?
11
Potassium
Hydrogen
Carbon
Neon
Calcium
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