Download Counting the electron shells in a neutral atom

9/7/2014
ALEKS Alex H. Yuan - 09/07/2014 10:14:32 PM EDT - Copyright © 2014 UC Regents and ALEKS Corporation
Alex H. Yuan - 09/07/2014 10:14:32 PM EDT
General Chemistry (First Semester) / Chem 110 FA 2014 – CH110 FA14 S25-36 (Dr.
Barber)
1.
Counting the electron shells in a neutral atom
Fill in the missing information about the atoms in the table below.
symbol
number of
protons
number of electrons
total
valence
number of
electron shells
You can answer this question by using the Periodic Table. Where you find an element in
the Periodic Table tells you a lot about what's inside atoms of that element:
The atomic number of an element tells you the number of protons and electrons in a
neutral atom of the element. For example, the element chlorine (symbol
) has
atomic number
That tells you there are
protons and
electrons in a neutral
atom of chlorine.
The group in which you find an element tells you the number of valence electrons in a
neutral atom of the element. For example, you'll find chlorine in Group
That
means a neutral atom of chlorine has valence electrons. Oxygen is in Group
That means a neutral atom of oxygen has valence electrons.
The period in which you find an element tells you the number of electron shells in a
neutral atom of the element. For example, chlorine is in Period That means a
neutral atom of chlorine has electron shells. Oxygen is in Period
atom of oxygen has electron shells.
so a neutral
Now let's apply these general principles to the specific problem you've got:
The atomic number of rubidium (symbol
) is
so there are
protons and
electrons in a neutral
atom. Also, rubidium is in Group
so there is valence
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9/7/2014
ALEKS Alex H. Yuan - 09/07/2014 10:14:32 PM EDT - Copyright © 2014 UC Regents and ALEKS Corporation
electron in a neutral
of electrons in a neutral
atom. Finally, rubidium is in Period
so there are
shells
atom.
The atomic number of potassium (symbol
) is
so there are
electrons in a neutral
atom. Also, potassium is in Group
electron in a neutral
atom. Finally, potassium is in Period
of electrons in a neutral
atom.
protons and
so there is
so there are
valence
shells
The atomic number of lithium (symbol ) is so there are protons and
electrons in a neutral
atom. Also, lithium is in Group
so there is valence
electron in a neutral
atom. Finally, lithium is in Period so there are shells of
electrons in a neutral
atom.
Since all three atoms in this problem are from the same group, they have the same number
of valence electrons. However, since they are from different periods, they have different
numbers of electron shells.
Here is the completed table:
symbol
number of
protons
number of electrons
total
valence
number of
electron shells
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