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Date: October 7, 2015
Aim #14: What determines an atom’s reactivity?
Do Now: Warm-Up Notebook
Date
10/7
Title of Activity
Analyzing Chemical Formulas
Page #
26
HW:
1) Worksheet- Practice with Atoms and Ions
2) Textbook Guided Reading 2-1 due Tuesday
10/13
Meet the Elements
https://www.youtube.com/watch?v=d0zION8xjbM
Review of Atoms:
P
N
Nucleus
(protons and neutrons)
Electrons
The protons and neutrons have a much greater mass than
the electrons.
Where are the electrons?
The electrons continually move around the nucleus
at great speed.
The attraction between the (-) charged electrons and the
(+) charged protons keeps the electrons close to
nucleus.
What are the differences between
elements?
What is the atomic
number of Helium?
2
An important difference among elements is the #
of protons in their atoms.
Atomic Number – the number of protons of an
element.
Can we find this information on the
Periodic Table?
**Notice, that no two elements have the same atomic
number.
Atoms tend to be electrically
neutral
What does that mean?
Atoms, if left alone, typically have the same number
of protons and electrons.
How many protons should this
atom have if it is electrically
neutral?
11
What is its atomic number?
11
What is an Ion?
An atom that has a positive
or negative charge due to
a loss or gain of
ELECTRONS!
Cation (+ Ion) – due to loss of an electron.
Anion (- Ion) – due to gain of an electron.
Brain Pop- Ions
https://www.brainpop.com/science/mattera
ndchemistry/ions/
Atomic Number vs. Mass Number
The atomic number is the number of protons found
in an element.
The mass number is the number of protons plus the
number of neutrons.
Mass number = protons + neutrons
What is the mass number of Carbon?
How many protons does Oxygen have?
12
8
How many neutrons does Sodium have? 11
Date: October 8, 2015
Aim #14: What determines an atom’s reactivity?
Do Now: Warm-Up Notebook
Date
10/8
Title of Activity
Simple Chemistry Review
Page #
27
HW:
1) Worksheet- Practice with Ions and Isotopes
2) Textbook Guided Reading 2-1 due Tuesday
10/13
What is an Isotope?
C-12
C-13
Mass
Number
C-14
Isotopes of an element have the same number of
protons in their atoms but different numbers of
neutrons.
Brain Pop- Isotopes
https://www.brainpop.com/science/mattera
ndchemistry/isotopes/
Practice Problems
1)How many protons in O-17?
8
2)What is the atomic number of C-13?
6
N
3) What element has an atomic number of 7?
4) What is the mass number of an element with
14
8 protons, 6 electrons, and 6 neutrons?
5) How many electrons does C-14 have?
6
What determines an atom’s
reactivity?
Electrons
2nd energy level
(8 electrons max)
1st energy level
(2 electrons max)
1st energy level
(2 electrons max)
Usually it is the electrons in the highest energy level
of an atom that determine how that atom reacts
How do we know if an element is
reactive?
If an element has partly-filled outer energy levels
This condition makes these elements chemically
reactive.
Rules in filling energy levels:
1)Determine the number of electrons the atom has.
2)Remember, the 1st energy level can hold 2
electrons and the 2nd energy level can hold 8
electrons.
3) Fill the lowest energy levels first.
Practice Problems:
1)If an atom has 9 electrons, how many electrons are
in the second energy level?
7
2)Is He a reactive element? Why?
No
3)How many free spaces are present in the second
level of F? 1