“Electron configuration and valence electron”
Competency
Standards :
1.
Determine the atomic structure, periodic properties of elements and chemical
bonds and molecular structure and properties
Basic Competency :
1.1
identify the atom, atomic structure, the properties of elements, relative
atomic mass, and the periodic properties of the periodic table
INDICATOR
- Determine the type and period
elements in the periodic table
- Determine the valence electron of elements from electron
configuration
MATERIALS
ELECTRON CONFIGURATION AND VALENCE ELECTRON
Electrons are atomic particles that are very light so that
its mass is negligible and is considered equal to zero. In an atom, the number
of electrons equals the number of protons, but kind of opposite charge. The
location is outside the core electron. That is contained in the electron
trajectories.
According to Bohr's atomic theory, electrons are in a
particular orbital trajectory or the so called shell electron. Each shell has a certain energy level. The closer
to the nucleus, the smaller the energy level. Conversely, the farther from the
nucleus, the greater the energy level. Based on its distance from the nucleus,
there are some shell.
First
shell or K shell
Second
shell or L shell
Third
shell or M shell
Fourth
shell or N shell
|
K
shell < L shell < M shell < N shell
|
a.
Electron configuration
Electrons in the atom is composed
based on the level of energy. Preparation of the electron is known as the electron configuration. There are
two ways of preparation of the electron, namely:
-
How a shell (K L M N) and
-
How a subshell (s p d f)
The second way (a subshell) will be discussed in class XI.
Currently, you will only be allowed with the electron configurations per shell
(KLMN).
Electron configuration of a shell based on the maximum
number of electrons that can fill each shell according to the formula
Σ e
maximum a shell = 2 (n2)
n
indicates the price of the occupied electron shell.
The
maximum number of electrons in every shell
Electron charging sequence starting from the shell which has
the lowest energy level, then the next shell that has a higher energy, until at
last the shell that will be occupied by the electron rest.
How if the number of electrons that are available do not
reach the maximum number of electrons in the shell, even greater than the
maximum electron shell before? If so, that would be occupied electron shell
should use the same number of electrons with the maximum number of electrons in
the shell before.
a.
Valence electron
Valence electron is an electron that
is located on the outer shell so that have the highest energy level. This
valence electrons involved in chemical reactions. Outer shell electrons can be
separated, interchanged, or used in conjunction with other atoms to form bonds
between atoms. In other words, the chemical nature of atoms is determined by
the valence electron.
How do I determine the valence
electron? Valence electrons can be determined by using electron configuration.
Determination of the valence
electron from the electron configuration
By determining the electron configuration, you can know the number of electrons in its outer shell.
By determining the electron configuration, you can know the number of electrons in its outer shell.
b.
Relationship type, period, electron
configuration and valence electron
You have studied the group, period,
electron configuration and valence electron, is there any relationship between
these four things?
Class of an element shows the number
of valence electrons. The period of an element indicates the amount of shell
that has been charged electron. Valence electron and the amount of shell that
has been filled electron can be determined from the electron configuration.
Thus, it can be seen from the electron configuration of the group number and
period of an element.
QUESTION
1. Write the electron configuration
of the following elements:
a. 9F
b. 11Na
c. 20Ca
d. 37Rb
e. 55Cs
f. 85At
2.
Determine the number of valence electrons of
atoms 35Br
3.
Determine the type and period of the
following elements!
a. 7N
b. 12Mg
c. 33As
d. 54Xe
e. 82Pb
ANSWER
1. Electron configuration from :
a. 9F : 2 7
b. 11Na : 2 8 1
c. 20Ca : 2 8 8 2
d. 37Rb : 2 8 18 8 1
e. 55Cs : 2 8 18 18 8 1
f. 85At : 2 8 18 32 18 7 (Score 30)
2. Electron configuration 35Br
: 2 8 18 7
In
the shell-4 which
is the outer shell, there are
7 valence electrons,
so the number of electron 35Br is 7 (Score 20)
3. Group and the period of:
a. Electron configuration 7N:
2 5
- Valence electrons 5, means the group VA
- There are two shell filled with electrons (n = 2), means a period of 2
- Valence electrons 5, means the group VA
- There are two shell filled with electrons (n = 2), means a period of 2
b. Electron configuration 12Mg
: 2 8 2
- Valence electrons 2, means the group IIA
- There are three shell filled with electrons (n=3), means a
period of 3
c. Electron configuration 33As
: 2 8 18 5
- Valence electrons 5, means the group VA
- There are four shell filled with electrons (n=4), means a
period of 4
d. Electron configuration 54Xe
: 2 8 18 18 8
- Valence Electron 8, means the group VIIA
- There are five shell filled with electrons (n=5), means a
period of 5
e. Electron configuration 82Pb
: 2 8 18 32 18 4
- Valence Electron 4, means the group IVA
- There are six shell filled with electrons (n=6), means a
period of 6 (Score 50)
Final score
= total score
of each number
The number of total score = 100
The number of total score = 100
