Download Scientific Method and Atomic Structure: A Brief Review

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Scientific Method and Atomic Structure: A Brief Review
Review of Standards: IE 1b, IE 1f, IE 1j, Chemistry 1e, Chemistry 1a, Chemistry 1b
A ___________________ is an educated guess that is proposed by a scientist when he attempts to answer a
question about the world. This ___________________ must be repeatedly tested and supported if it is going to
become part of a ________________. A ______________ is well accepted and is used to explain the answer to
a very broad question.
You are growing two plants at opposite ends of a garden to see which side has better nutrients in the soil. Even
if you buy the same type of plant, it is likely that the two plants have slight difference that may affect your
results. These differences are a source of unavoidable experimental ____________. Experimental errors are
minimized by having _______________ variables. These are factors that you keep the same for all trials.
All elements are made of _____________________________. All elements are listed on the
__________________. They are organized in order of _________________. The atomic number tells you the
number of ________________ in an atom of that element.
The atomic mass is also found on the __________________. Atomic Mass = number of ______________ +
number of _______________. This is nearly the total mass of the atom. Protons and Neutrons are found in the
____________. Therefore, the ______________ contains almost all of the mass of the atom. However, it has a
VERY small volume compared to the rest of the atom, so the nucleus is the most ___________ part of the atom.
The size of an atom’s electron cloud is much ________________ than the size of the nucleus.
___________________ are located in the electron cloud in energy levels, or ___________. Electrons will
always fill the __________ energy level available. The electrons in the outermost electron shell are called
____________ electrons. In a neutral atom, the number of electrons is equal to the number of _____________.
Opposite charges __________ and like charges __________. This means that the ______________ nucleus is
attracted to the _______________ electrons and pulls them towards the nucleus.
Elements found on the left and middle of the periodic table are _________________. They are
_______________________ of heat and electricity. _____________ are found of the right side of the periodic
table. Semi-metals are found ______________________________________.
Element
Atomic
Symbol
Atomic
Number
Atomic
Mass
Period
#
Group
#
3
15
Helium
4
#
Protons
# Neutrons
#
Electrons
Draw It (you can use
a separate sheet)
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Elements, Atoms, and the Periodic Table Activity
Review of Chemistry 1a, 1d, 1c
Activity: Building Atoms
You should have 10 of each note card color. Blues are protons, purples are neutrons, and yellows are electrons.
For each of the below elements, build an atom using the note cards and chart paper. Then, fill in the blanks for
each of the below categories. Round the atomic mass to the nearest whole number. Put a box around the number
of valence electrons.
Name
Atomic
Number
Atomic
Mass
# p+
#n
# e-
Group
e- in 1st
energy level
e- in 2nd
energy level
e- in 3rd
energy level
Chlorine
Argon
Sodium
Lithium
Fluorine
Neon
Using the chart, choose the three pairs of elements that are in the same group:
Group 1. Element:
Group #:
Number of Valence e-:
Period #:
# of e- shells:
Group common name:
Observations:
Element:
Group #:
Number of Valence e-:
Period #:
# of e- shells:
Group 17. Element:
Group #:
Number of Valence e-:
Period #:
# of e- shells:
Group common name:
Observations:
Element:
Group #:
Number of Valence e-:
Period #:
# of e- shells:
Group 18. Element:
Group #:
Number of Valence e-:
Period #:
# of e- shells:
Group common name:
Observations:
Element:
Group #:
Number of Valence e-:
Period #:
# of e- shells:
Elements in the same group have the same number of _______________________. So…why does that matter?
Many of the properties of an element are determined by its number of valence electrons.
Therefore, elements in the same _____________ have similar _________________.
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Practice: Answer the following multiple choice questions
1. Beryllium has properties most like:
2. Oxygen has properties most like:
a. Lithium
a. Hydrogen
b. Boron
b. Sulfur
c. Neon
c. Carbon
d. Calcium
d. Neon
3. Choose the group of elements that have similar properties
a. Carbon, Nitrogen, and Oxygen
b. Neon, Argon, and Helium
c. Aluminum, Germanium, and Arsenic
d. Calcium, Scandium, and Titanium
Periodic Trends: Atomic Radius
Chemistry 1c. Students know how to use the periodic table to identify alkali metals, alkaline earth metals and
transition metals, trends in ionization energy, electronegativity, and the relative sizes of ions and atoms.
The periodic table is full of patterns. In addition to predicting the number of electron shells, valence electrons,
and properties, you can also determine the relative sizes of atoms, their electronegativity, and their ionization
energy. Today we will only focus on determining the relative size, or _______________, of an atom.
What is a radius in math?
What is atomic radius?
What does relative mean?
Atoms come in different sizes. Their sizes are determined by the number of _________________. As more
shells are added, the atom becomes _________________. Therefore, the atomic radius _______________ as
you move down a group.
Example: Barium (56) is bigger than Beryllium (4). Why?
Key Point: Atomic radius increases (the atom gets bigger) as you move down a group.
Concept check: Compare Oxygen to Sulfur. Which atom is bigger? Why?
The size of an atom is also determined by how tightly the positive _______________ can attract the negative
______________________. If there are more ______________ in the nucleus, it has a greater positive charge
and can pull the electrons closer. As you move from left to right across a ____________, the number of protons
__________________, but the number of electron shells ____________________. Therefore, atoms get
_____________ as you move from left to right across a period.
Example: Fluorine (9) is smaller than Lithium (3)
Key Point: Atomic radius decreases (the atom gets smaller) as you move from L to R across a period.
Concept Check: Compare Aluminum to Silicon. Which atom is bigger? Why?
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Class Period:
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Rewrite the key points here:
1.
2.
From this information, we conclude that
________________ has the smallest atomic radius
and _______________ has the largest atomic radius.
Practice: Atomic Radius
1. Which atom has a larger atomic radius
than Calcium (20)?
a. Lithium (3)
b. Barium (56)
c. Magnesium (12)
d. Bromine (35)
2. Which element has the smallest atomic
radius?
a. Oxygen (8)
b. Nitrogen (7)
c. Sulfur (16)
d. Phosphorus (15)
3. Which element has the largest atomic radius? Explain why this atom has the largest atomic radius.
Step 1: Answer the first part of the questions (which element has the largest atomic radius) in a
complete sentence.
Step 2: Answer the second part of the question by explaining why this element is the largest. Begin
by restating what the question asks. Since it is a why question, you should use the word because after you
restate the question. Then, support that statement by discussing the reason that it is true. You know that
there are 2 factors for determining size of the atom, so you must discuss both.
First, start your explanation by stating:
Francium has the largest atomic radius because…
Then explain why atomic radius is largest at the bottom of a group.
Elements at the bottom of a group have the largest atomic radius because…
Then explain why atomic radius is largest at the left side of a period.
Elements at the left of a period have the largest atomic radius because…
Then, state why this makes that element the largest overall.
Since elements are largest at the left side of a period and bottom of a group, the largest element is
located…