Valence Electrons and Electron Configuration Explaining the arrangement of electrons 08/27 & 08/28.
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Transcript of Valence Electrons and Electron Configuration Explaining the arrangement of electrons 08/27 & 08/28.
Valence Electrons and Electron Configuration
Explaining the arrangement of electrons
08/27 & 08/28
Catalyst• Take out your HW to be stamped.• On your Daily Work Organizer, fill
in your goal for the week.• Catalyst: Describe the pictured
substances.
Video Clip: Reviewhttp://www.youtube.com/watch?v=1PSzSTilu_s&feature=bf_prev&list=PL65159266CFC74682
Homework BaseballAnswer the questions on a blank
sheet of paper. Use your homework.
1. Why are the noble gases the least reactive elements?
2. In the electron configuration 1s2, the 1 represents the:
(a) number of protons (b) number of electrons (c) the energy level
Homework Baseball: Answers
1. Why are the noble gases the least reactive elements? They have a full shell of valence electrons.
2. In the electron configuration 1s2, the 1 represents the:
(a) number of protons (b) number of electrons (c) the energy level
Objectives
• SWBAT draw Lewis dot diagrams.• SWBAT write electron configurations.• SWBAT explain the octet rule and use
it to predict ion formation.
Agenda
• Catalyst• Electrons and Intro to Ions• Mystery Elements Puzzle• Exit Ticket
Properties of the atom
• Protons determine the physical properties– The number of protons makes the
element• Electrons determine the chemical
properties– Only the electrons react!!!
Electron Energy Levels• In the electron cloud, electrons are arranged
in energy levels (aka orbitals or shells). • Electrons fill the levels from the inside out.• Electrons in the outer shell form chemical
bonds (react) with other atoms.
1
2
3
4
5
6
7
Write: periods tell us energy levels
What are valence electrons??
• Valence electrons are electrons on the outer shell of an atom that are available for bonding.
– Valence Electrons are VERY IMPORTANT, they determine an element’s reactivity and general characteristics
1 23 7654 8
Write: groups tell us # valence electrons
Practice: Draw the Bohr model and Lewis Dot Structure for N, O, F, Ne,
Na, and Mg.Note: 1st orbital has 2 e, 2nd and 3rd orbitals
have up to 8 e.• Lewis Dot
symbols show us how many valence electrons are in an atom.
• Bohr models show us all the electrons, separated by energy level (orbital).
Li
Ions!• Octet Rule: When forming ions,
atoms give or take electrons in order to have a full outer orbital (or shell).– They end up with the same number
of electrons as the closest noble gas. This is usually 8. (Exception: Helium with 2.)
Think, pair, share.
• How many electrons would N, O, F, Na, & Mg lose or gain to have the same number of electrons as Ne?
• What ions are formed?• Example: Lithium loses 1 e to
form Li+ (same # e as He)(Work with the person next to you
and write your answers under your Lewis Dot structures in your notes.)
Ions! Cations and Anions• Ion = an atom that has gained or
lost electrons – Ions have a negative or positive
charge.
• Anion = ion with a negative charge.– Usually nonmetals
• Ex: Cl- S2-
• Cation = ion with a positive charge.– Usually metals
• Ex: Be2+ Al3+
Think, Pair, Share
• Are the ions of N, O, F, Na, and Mg cations or anions?– Label them in your notes.– Then share with your partner.
• Does Ne form an ion? Why not?
Electron Configuration
• A way to keep track of all those electrons!
• Write this down:
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6
http://www.youtube.com/watch?v=Vb6kAxwSWgU
© 1998 by Harcourt Brace & Company
S orbital P orbital
D orbital
F orbital
1234567
67
Within the Energy Levels, electrons are arranged in 1 or
more orbitals. Label the orbitals on your periodic table.
Orbitals
S
p d f
Each orbital within a level has:• different energies• different shapes• Different orientation in space
s-block
1st Period
1s1# e- in sublevel
1 2 3 4 5 6 7
Periodic Table &
Electron Configuration• Example - Hydrogen
1 2 3 4 5 6 7
p-block
2nd Period
1s22 e- in p sublevel
• Example - Carbon
2s22p2
XXX
XXX
Periodic Table & Electron Configuration
1 2 3 4 5 6 7
p-block
2nd Period
[He]
Short Hand Configuration
• Example - Carbon
2s22p2
XXX
XXX
S 16e-
Valence Electrons(Outer shell)
Core Electrons (Inner orbitals)
1s2 2s2 2p6 3s2 3p4
Notation
• Longhand Configuration
Let’s Try It!• 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6
Practice! Write the electron configuration for the following elements:N, O, F, Ne, Na, Mg
Write your answers under your Bohr models and Lewis Dot Structures for these elements.
Agenda
• Catalyst• Electrons and Intro to Ions• Mystery Elements Puzzle• Exit Ticket
Mystery Elements Puzzle
• Work in a group of 4 at your table• Use the clues and your periodic
table to match each symbol with an element.
• Write down your answers on a sheet of paper.
• Raise your hand when you think you have solved the puzzle.
Exit Ticket
1. Draw the Bohr model and Lewis Dot Structure for Phosphorus (P).
2. Write the electron configuration of P.
3. How many electrons will P lose or gain to form an ion? How do you know?
4. What ion does P form? Is it an anion or cation?
If you are done, work on HW packet.