Download STAAR Tutorial #2: Energy and Matter Atoms

Name: ___________________________ Teacher: _______________ Pd. ____ Date: ___________
STAAR Tutorial #2: Energy and Matter
8.5A Describe the structure of atoms, including the masses, electrical charges,
and locations of protons and neutrons in the nucleus and electrons in the
electron cloud.
8.5D Recognize that chemical formulas are used to identify substances and
determine the number of atoms of each element in chemical formulas
containing subscripts.
Atoms
•
Atoms are the tiny particles that make up matter.
•
Atoms are the simplest form of an element and each element is
made of only one kind of atom. Example would be gold is made of
gold atoms and neon is made of neon atoms.
Practice Problem: What would Polonium be made of?
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•
The atom is made of 3 main parts: proton, neutron, and electron
(also called subatomic particles).
•
Each atom has a nucleus located in the center and an electron cloud
which is mostly empty space outside of the nucleus.
•
Protons and Neutrons are located in the nucleus and Electrons
are located in the electron cloud outside the nucleus.
•
Below are examples of different drawings of an atom:
Protons
Neutrons
Nitrogen Atom
Beryllium Atom
•
Each subatomic particle has characteristics:
Subatomic particle
Approximate
Atomic Mass
(amu)
Proton
Neutron
Electron
•
1
1
0
Charge
Positive (+)
None (0) neutral
Negative (-)
Location in
Atom
Nucleus
Nucleus
Electron Cloud
The periodic table gives information about how many atoms of each of these
particles are found in the atoms for each element.
o Example: Sodium has an atomic number of 11 which means it
has 11 protons and 11 electrons. Sodium’s atomic mass is 22.990,
and to find the number of neutrons you have to round to the
nearest whole number 23 and then subtract the atomic number
(23-11=12 neutrons).
•
Helpful Hint: Remember APE=Atomic number, Proton, Electron all will have
the same number.
Practice Problems:
Element Name
Atomic Number
Helium
2
Beryllium
4
Boron
5
Fluorine
9
Aluminum
____
Phosphorus
____
Chlorine
____
Protons
2
4
____
____
____
____
____
Electrons
2
4
____
____
____
____
____
Neutrons
2 (4-2)
5 (9-4)
____ (11-5)
____
____
____
____
Practice Problem:
Draw an atom of the element Nitrogen placing charges for each
subatomic particle (+ for positive and – for negative) inside of
each circle.
Example of Helium:
Nitrogen Atom:
Practice Problem:
Which elements are pictured below?
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Chemical Formulas
•
Scientists use element symbols and subscript numbers instead of
words to show which elements combine to make new substances.
•
A chemical formula shows the number and types of atoms in one molecule of
the compound.
Symbol for
hydrogen
Symbol for
oxygen
H 2O
Number of
hydrogen
atoms
(subscripts)
•
Number of
oxygen atoms
(no subscript
means one atom)
Other examples of chemical formulas:
H2 O 2
C2H4O2
NaHCO3
Hydrogen peroxide
Vinegar/Acetic Acid
Baking Soda
NH4
Ammonia
C6H12O6
Glucose
•
When determining how many atoms of each element are in a
formula you have to look at each element (remember: symbols for
elements are 1 or 2 letters. If it is a 2 letter symbol the first letter
will be capitalized and the second letter will be lowercase.
Example: symbol for Mercury is Hg).
•
Additional information/hint: if asked how many elements are in a
formula an easy way is to count the capital letters: H2SO4 = there
are 3 elements in that formula.
Practice Problems:
How many atoms of each element are in each formula?
H 2 O2
H2SO4
NaHCO3
Hydrogen=___
Oxygen=___
Hydrogen=____
Sulfur=___
Oxygen=____
Sodium=____
Hydrogen=____
Carbon=____
Oxygen=____
***if you need more practice go back to previous page and count the
atoms for each element in the section about other examples of
chemical formulas.***
Extra Problem (challenge):
How many atoms of Hydrogen were combined to form water in the
equation below? __________
2H2 + O2 2H2O
This problem above is a chemical equation. Also take note of the big
number on the left next to the first Hydrogen-it is called a coefficient.
The two items will be addressed in the next tutorial, so if you didn’t
get the correct answer now then maybe you will later☺