DUE NOW (10 MINUTES) Warm-ups (9/8 – 9/11) [4 total]
Homework #9 & Homework #10
Classwork: 5 PRACTICE PROBLEMS (Converting moles/grams)
Chapter 3 Study Guide
ATOMIC ZOOAnimal Name
Element NamesComposed Of?
Atomic # Cage #
Atomic Mass (total) Weight
LiON Li -Lithium O -OxygenN -Nitrogen
Li –3 O - 8N- 7
6.94 16.00 14.01TOTAL: 36.95
BeAr Be- BerylliumAr- Argon Please complete 10 (15
E.C.)
WARM-UP (9/15/14) Draw the Bohr model of an atom. What was the main feature of this model?
PERIODIC TABLE How is the periodic table organized?
Vertical column = groupHorizontal row = period
BOHR’S MODEL & ELECTRONS
Electron shells surround the nucleus and each hold a certain number of electrons
1. First shell holds 2 electrons2. Second shell 8 electrons3. Third shell 18 electrons
THE OUTER SHELL OF AN ATOM CAN ONLY HOLD 8 ELECTRONS
BOHR DIAGRAM OF CARBON
1. Find your element on the periodic table
2. Find the atomic number protons and # Electrons (e-)
Protons? Neutrons? Electrons?
Outermost electrons are called valence electrons
PRACTICE: HELIUMDraw the Bohr diagram for Helium
Protons?Neutrons?Electrons?
REMEMBER: LOW HIGH
1.1st shell holds 2 electrons
2.2nd shell 8 electrons3.3rd shell 18 electrons
Work on WS now.
WARM-UP (09/16) Draw the Bohr diagram for Silicon.
How is it similar to carbon’s diagram?
BOHR MODEL PERIODIC TABLE
What can these diagrams tell us about the groups (vertical columns) in the periodic table?All elements in the same group…
What can these diagrams tell us about the periods (horizontal rows) in the periodic table?All elements in the same period…
Why might valence electrons be important?
THE PERIODIC TABLEValence electrons allow an atom to participate in chemical reactions
Groups tell us how many valence e- there are
Periods tell us how many e- shells there are
WARM-UP (09/17)
Draw the Bohr diagram for magnesium.
Which period is it in? (Period # ______ )
Which group is it in? (Group # ______ )
POP QUIZPlease take out 1 sheet of paper and rip it in half. You will use the other half at the end of class
POP QUIZ
1. Draw the Bohr diagram for nitrogen.2. The electrons in the outermost shell
are called _______________ electrons.3. What do all elements in the same
group share? Ex. All elements in the same group…
4. What do all elements in the same period share?
HISTORY OF THE PERIODIC TABLE (1865) John Newlands – law of octaves similar properties every eight elements Order based on atomic mass
(1869) Dmitri Mendeleev first periodic table (63 known elements at the time)Some elements didn’t “fit” correctly(by atomic mass)
HISTORY OF THE PERIODIC TABLE
HISTORY OF THE PERIODIC TABLE
Henry Moseley realized the periodic table should be organized by atomic ____________, NOT atomic _____________.
This “fixed” Mendeleev’s periodic table
THE MAIN-GROUP ELEMENTS
Groups 1-2, 13-18 are known as ________________________.
Electron behavior is regular and consistent
GROUP 1 – ALKALI METALS
GROUP 1 – ALKALI METALSList some characteristics of Alkali metals.
SoftHighly reactiveReacts with air Reacts (violently) with water
EXIT SLIP (ANSWERS ONLY)
1. List two properties of Alkali Metals
2. Why do all elements in the same group share similar properties? (Think about what they have in common)
WARM-UP (09/18) Why do all elements in the
same group share similar properties? (Think about what they have in common)
[You may want to review Bohr diagrams of same-group elements]
Predict how many valence electrons are in Strontium (Sr). Explain your answer.
GROUP 1 – ALKALI METALS
GROUP 1 – ALKALI METALSList some characteristics of Alkali metals.
SoftHighly reactiveReacts with air Reacts (violently) with water
GROUP 2 - ALKALINE EARTH METALS
How many valence electrons? Very reactive (not as much as alkali metals)
Ex. Be, Mg, Ca, Sr, Ba
Please write down characteristics of halogens during the video
GROUP 17 - HALOGENS
GROUP 17 - HALOGENS
How many valence electrons? Properties?Most reactive group of nonmetal
elementReact with most metals to produce
salts
GROUP 17 - HALOGENS
GROUP 18 – NOBLE GASES
GROUP 18 – NOBLE GASES What is the main characteristic of noble gases?
They are unreactive & very stable
How do they achieve stability?
HYDROGEN IS TOO COOL
Behaves unlike any other element
Is in it’s own class!
GROUPS 3-12: TRANSITION METALS
Unlike main group elements, the electrons may vary
Ex. Copper, platinum, gold, silver, iron
EXIT SLIP
What are some properties of metals that you know of?
What seems to be the “magic number” when it comes to valence electrons? (Hint: what makes an atom stable)
HAPPY FRIDAY! NOW TURN IN YOUR WORK
You have 7 minutesDUE NOWWarm-Ups (9/15 – 9/18)
HW #11 (complete)& HW #12
WARM-UP (09/23/14) Periods, or rows, tell us how many__________ __________ are in an atom.
As you move DOWN a group, what do we notice about the number of electron shells?
GUIDED NOTES REVIEW“What is the f in the box mean?” “Why does it matter if an atom is
‘happy’” ?“What is it called when you add an
electron?” “How does an atom change when it
loses an electron?”“How can you have different
numbers of protons and electrons?”
IONIZATION ENERGY AND ELECTRON SHIELDINGWhat is ionization energy? The energy required to remove an electron from an atom or ion
Compare Lithium and Potassium
Li K
IONIZATION ENERGY AND ELECTRON SHIELDINGCompare Lithium and Potassium
Li K
Potassium (K) has more __________ between it’s valence electron and the nucleus
Electron shielding causes valence e- to be held less tightly to the nucleus
ELECTRONS ARE LIKE CONCERT-GOERS
The band is the nucleus (+) Closer you are to the band, the less
you can moveIf you’re further out, you can easily
leave the concert
The more people between you and the band, the less attracted you are to the concert
IONIZATION ENERGY TRENDS
Remember, ionization energy is the energy needed to remove an electron
Ionization energy decreases as you go down a group
Ionization energy increases as you go across a period.
Li Ne
IONIZATION ENERGY TRENDS
Think of it as 3 magnets vs. 10 magnets
More protons greater effective nuclear charge
Ionization energy increases as you go across a period
Li Ne
ATOMIC RADIUSAs you go down a group, you add
another electron shell.
Li
K
As you go down a group, the atomic radius will increase.
ATOMIC RADIUS TRENDS
3 magnets vs 10 magnetsMore protons greater effective nuclear charge
Protons “pull” the electrons closer in
Atomic radius decreases as you go across a period
Li Ne
ELECTRONEGATIVITY
Electronegativity – a measure of the ability of an atom in a chemical compound to attract electrons
Electronegativity decreases as you go down a group Electron shielding prevents protons
from attracting electronsElectronegativity increases as you go across a period
EXIT SLIP (ANSWERS ONLY)1. Write the periodic trends for
TWO properties discussed today
Ex. As you go down a group, _________ will increase/decrease and as you go across a period…
2. For you, what is the most difficult thing we have learned about in chapter 4 (Bohr/periodic table)?
WARM-UP (09/24/14)
What is ionization energy? Which group would have the lowest ionization energy?
What is electronegativity? Which group would have the highest electronegativity?
WHOLE CLASS REVIEWDraw the Bohr diagram for oxygen Groups are GUD (Go UP and
DOWN/vertical) Periods are LONG (side to side/ horizontal) All elements in the same ___________ have
the same number of valence electrons.Ex. All elements in the first group have ___
valence electron.All elements in the same ___________ have
the same number of electron shellsEx. All elements in the 3rd period have _____
e- shells
REVIEW OF YESTERDAY: GROUP TRENDS
As we go down a group, we add an electron shell.
This causes more electrons to be between our nucleus (+) and our valence electrons ( - ).
This makes it easier to remove valence electrons because more electrons SHIELD or BLOCK the positive charge coming from the nucleus
Li
Na
REVIEW OF YESTERDAY: GROUP TRENDS
If there is more electron shielding, it is easier to remove an electron (Ionization energy decreases)
But it is harder to attract electrons (Electronegativity decreases)
More shells increase in atomic radius
Li
Na
REVIEW OF YESTERDAY: GROUP TRENDS
As we go across a period, we add protonsThis causes the nucleus (+) to have a
greater positive pull on electrons (-)This makes it harder to remove valence
electrons because more protons are holding the electrons closer to the nucleus
Li Ne
REVIEW OF YESTERDAY: GROUP TRENDS
If it is harder to remove electrons, it requires more energy (Ionization energy increases)
More protons mean they can attract electrons more easily (Electronegativity increases)
More protons mean they pull electrons closer towards the nucleus (Atomic radius decreases)
Li Ne