Electronic Configuratoin -Grade 8 Science

• An atom has 3 sub-atomic
particles namely: protons,
electrons, and neutrons. Protons
are the positively charged
particles, electrons are the
negatively charged and neutrons
are the neutrally charged or no
charge particles.

• Inside the atom is the massive
center called nucleus where
protons and neutrons are located.
What is the charge of the nucleus
then? Electrons on the other hand
are located outside the nucleus.
These electrons circle the nucleus
in an orbit-like structures called
energy level.

Activity 1. Let’s Pretend!
Let’s pretend we are moving students into campus housing.
• The housing is on the 1st, 2nd, 3rd and 4th street (the levels).
There are houses on these streets.
•The houses are called s, p, d and f houses. Each street has the
following type of houses: 1st
=s; 2nd
= s & p; 3rd
=s,p,d; 4th
= s,p,d, & f.
•The s house has 1 bedroom, the p house has 3 bedrooms, and d
house has 5 bedrooms, and the f house has 7 bedrooms.
•In each bedroom there is a bunk bed, so two students can sleep in a
bedroom.

ANSWER THE QUESTIONS:
1. How many houses are there on the 4th street?
2. How many students can live on the 3rd street?
3. How many bedrooms are on the 2nd street?
4. How many students can live in a p house?
5. How many bedrooms are there in a p house?
6. How many bedrooms are present in an f house?
7. How many students can live in an f house?
8. How many students can live on the 1st street?
9. How many students can live on the 2nd street?
18
4 Name them. s,p,d,f
4
8
3
7
32
2
8

Electron Configuration
1s1
row #
shell #
possibilities are 1-7
7 rows
subshell
possibilities are
s, p, d, or f
4 subshells
group #
# valence e-
possibilities are:
Total e- should equal
Atomic #

Electronic Configuratoin -Grade 8 Science

Electrons exist around the nucleus of an atom in specific
orbits. These orbits are called energy levels and we
number them 1, 2, 3, 4, 5,6 and 7 with the 1st level being
the orbit closest to the nucleus and is called the innermost
energy level or shell and the last energy level as the
outermost shell/energy level. The levels can be broken
down into sublevels. We have s, p, d, and f sublevels.
Level one has one sublevel – s. Level 2 has 2 sublevels - s
and p. Level 3 has 3 sublevels - s, p, and d. Level 4 has 4
sublevels - s, p, d, and f. The sublevels contain orbitals.

Orbitals are spaces that have a high probability of containing an
electron. In other words, an orbital is an area where the electrons
live. There can be two electrons in one orbital (maximum). The s
sublevel has just one orbital, so can contain 2 electrons max. The
p sublevel has 3 orbitals, so can contain 6 electrons max. The d
sublevel has 5 orbitals, so can contain 10 electrons max. And the
4 sublevel has 7 orbitals, so can contain 14 electrons max. Look
at the illustration, the orbitals are represented by the boxes. You
can put two electrons in each box. Some things to notice. Level
1 does not have a p or d or f sublevel, only an s sublevel. So
there is no such thing as 1p or 1d or 1f.

To illustrate this further, we will use electron
configuration. What is electron configuration?
Electron Configuration is a shorthand notation
for showing how the electrons are distributed in
the various energy level/electron shells. We fill
in electrons according to lowest energy sublevels
first. So we basically go in order: 1s, 2s, 2p, 3s,
3p. Remember for neutral atoms, the number of
protons equals the number of electrons.

Examples:
1.Carbon atom has 6 electrons
– 1s2
2s2
2p2
because 2+2+2=6
2. Silicon atom has 14 electrons
– 1s2
2s2
2p6
3s2
3p2
because
2+2+6+2+2=14

Electron configuration
- the way the electrons of an atom
are distributed in the various
energy levels or electron shell.

1
2
3
4
5
6
7
6
7
1A
2A
3B 4B 5B 6B 7B 8B 8B 8B 1B 2B
3A 4A 5A 6A 7A
8A
group # = # valence (outside) e-
d p
f
s
Row
=
# shells

1s1
• Energy level
• Row number
• Type of orbital
• subshell
• Number of electron
• s: 1 or 2
• p: 1-6
• d: 1-10
• f: 1-14

Activity 2. Find this out!
Direction: Give the electron configurations
of the following atoms:
1. Sodium
2. Boron

Aufbau Principle is the basic method that
tells us how the electrons are filled in the
atomic orbital. According to the Aufbau
Principle, the filling of the electrons in the
ground state of an atom follow a basic
pattern. This principle tells us that the
electrons in the atomic orbital of any atoms
are filled in the ascending order of their
energy and for finding the energy of the
atomic orbital.

Order of Electron Subshell Filling:
Aufbau mnemonic device it does not go “in order”
1s2
2s2
2p6
3p6
4p6
5p6
6p6
7p6
3s2
4s2
5s2
6s2
7s2
3d10
4d10
5d10
6d10
4f14
5f14
1s2
2s2
2p6
3p6
3s2
4s2
4p6
5s2
3d10
5p6
6s2
4d10
6p6
7s2
5d10
4f14
7p6
6d10
5f14
As you can see here in
the mnemonic device, the
order of filling the orbitals is
to be listed as 1s, 2s, 2p,
3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p,
6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p.
This order is followed in
writing the electron
configuration, distributing
the electrons in the
orbitals of the sublevels
as they are struck by
the consecutive arrows.

1
2
3
4
5
6
7
6
7
period
#
=
#
e-
shells
1A
2A
3B 4B 5B 6B 7B 8B 8B 8B 1B 2B
3A 4A 5A 6A 7A
8A
group # = # valence e-
d
f
3d
4d
5d
6d
4f
5f
Subshells d and f are “special”

Assessment:
Directions: Get the electron configuration of the
following element below. Write your answers on your ½
crosswise sheet of paper.
1. Mg:
2. Ar:
3. Ag:
4. Po:
5. Pu:

Correct Answer:
1. Mg: 1s2
2s2
2p6
3s2
= 12
2. Ar: 1s2
2s2
2p6
3s2
3p6
= 18
3. Ag: 1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p6
5s2
4d9
= 47
4. Po: 1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p6
5s2
4d10
5p6
6s2
4f14
5d10
6p4
= 84
5. Pu: 1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p6
5s2
4d10
5p6
6s2
4f14
5d10
6p6
7s2
5f6
= 94

Assessment:
1. Sr:
2. Xe:
3. Hs:
4. Tb:
5. Cf:

Assessment:
Directions: Get the electron configuration of the following
element below. Write your answers on your ½ crosswise sheet of
paper.
1. Sr: 1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p6
5s2
2. Xe:1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p6
5s2
4d10
5p6
3. Hs:1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p6
5s2
4d10
5p6
4f9
6s2
s2
7s2
5f14
6d6
4. Tb: [Xe] 6s2
4f9
5. Cf: [Rn] 7s2
5f10

Aufbau Principle Formula
The Aufbau Principle Formula is the formula that tells the order in which the
electrons are filled in the atomic orbital. The atomic orbital formula is
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p

Assessment:
Directions: Answer the questions below. Write your
answers on a separate sheet of paper.
1.What is the outermost shell of Sodium atom? Boron?
2.What is the outermost sublevel/subshell of Sodium?
Boron?
3.How many electrons are found in the outermost
energy level of Sodium? Boron?

What is Electronic
Configuration?
In atomic physics and quantum chemistry,
the electron configuration is the distribution of
electrons of an atom or molecule (or other physical
structure) in atomic or molecular orbitals.

How electrons are arranged
around the nucleus of an atom?
• The number of protons in the atom of
an element determines its place in the
Periodic Table.
• The number of electrons in an atom is
the same as the number of protons.
These electrons are arranged in shells or
'energy levels' around the nucleus.

What are the Subshells?
• A subshell is a subdivision of electron
shells or energy levels separated by
electron orbitals.
• Subshells are labelled s, p, d, and f in an
electron configuration. Examples: The first
electron shell is the 1s subshell. The
second shell of electrons contains the 2s
and 2p subshells.

• The block names (s, p, d, f and g) are
derived from the spectroscopic notation for
the associated atomic orbitals
: sharp, principal, diffuse and fundamental

1s1
row #
shell #
possibilities are 1-7
7 rows
subshell
possibilities are
s, p, d, or f
4 subshells
group #
# valence e-
possibilities are:
s: 1 or 2
p: 1-6
d: 1-10
f: 1-14
Total e- should equal
Atomic #
What element has an electron configuration of 1s1
?

Practice:
Ask these questions every time you have to write an
electron configuration
• Lithium:
1. find the element on the periodic table
2. what is the period number?
3. how many shells?
4. what is the group number?
5. how many valence electrons?
6. what subshell(s) does Li have?
7. what is the electron configuration?
atomic # = 3
2
2
1
1
s
1s2
2s1

Practice:
• Boron:
2. what is the row #?
3. how many shells?
4. what is the group #?
6. what subshell(s) does B have?
atomic # = 5
2
2
3
3
p
1s2
2s2
2p1

Practice:
• Sr:
3. how many shells?
6. what subshell(s) does Sr have?

Practice:
• N:
3. how many shells?
6. what subshell(s) does N have?

Practice:
• Xe:
3. how many shells?
6. what subshell(s) does Xe have?

Find the electronic configuration
of the ff:
1. Chlorine 4.Gallium
2. Krypton 5.Carbon
3. Lead
Using abbreviated electronic configuration:
1. Radon 4. Au
2. Francium 5. Copernicium
3. Nickel

Electronic Configuratoin -Grade 8 Science

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