<< Chapter < Page Chapter >> Page >
This figure includes electron configurations and orbital diagrams for four elements, N, O, F, and N e. Each diagram consists of two individual squares followed by 3 connected squares in a single row. The first square is labeled below as, “1 s.” The second is similarly labeled, “2 s.” The connected squares are labeled below as, “2 p.” All squares not connected to each other contain a pair of half arrows: one pointing up and the other down. For the element N, the electron configuration is 1 s superscript 2 2 s superscript 2 2 p superscript 3. Each of the squares in the group of 3 contains a single upward pointing arrow for this element. For the element O, the electron configuration is 1 s superscript 2 2 s superscript 2 2 p superscript 4. The first square in the group of 3 contains a pair of arrows and the last two squares contain single upward pointing arrows. For the element F, the electron configuration is 1 s superscript 2 2 s superscript 2 2 p superscript 5. The first two squares in the group of 3 each contain a pair of arrows and the last square contains a single upward pointing arrow. For the element N e, the electron configuration is 1 s superscript 2 2 s superscript 2 2 p superscript 6. The squares in the group of 3 each contains a pair of arrows.

The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the 3 s orbital, giving a 1 s 2 2 s 2 2 p 6 3 s 1 configuration. The electrons occupying the outermost shell orbital(s) (highest value of n ) are called valence electrons    , and those occupying the inner shell orbitals are called core electrons ( [link] ). Since the core electron shells correspond to noble gas electron configurations, we can abbreviate electron configurations by writing the noble gas that matches the core electron configuration, along with the valence electrons in a condensed format. For our sodium example, the symbol [Ne] represents core electrons, (1 s 2 2 s 2 2 p 6 ) and our abbreviated or condensed configuration is [Ne]3 s 1 .

This figure includes the element symbol N a, followed by the electron configuration for the element. The first part of the electron configuration, 1 s superscript 2 2 s superscript 2 2 p superscript 6, is shaded in purple and is labeled, “core electrons.” The last portion, 3 s superscript 1, is shaded orange and is labeled, “valence electron.” To the right of this configuration is the word “Abbreviation” followed by [ N e ] 3 s superscript 1.
A core-abbreviated electron configuration (right) replaces the core electrons with the noble gas symbol whose configuration matches the core electron configuration of the other element.

Similarly, the abbreviated configuration of lithium can be represented as [He]2 s 1 , where [He] represents the configuration of the helium atom, which is identical to that of the filled inner shell of lithium. Writing the configurations in this way emphasizes the similarity of the configurations of lithium and sodium. Both atoms, which are in the alkali metal family, have only one electron in a valence s subshell outside a filled set of inner shells.

Li: [ He ] 2 s 1 Na: [ Ne ] 3 s 1

The alkaline earth metal magnesium (atomic number 12), with its 12 electrons in a [Ne]3 s 2 configuration, is analogous to its family member beryllium, [He]2 s 2 . Both atoms have a filled s subshell outside their filled inner shells. Aluminum (atomic number 13), with 13 electrons and the electron configuration [Ne]3 s 2 3 p 1 , is analogous to its family member boron, [He]2 s 2 2 p 1 .

The electron configurations of silicon (14 electrons), phosphorus (15 electrons), sulfur (16 electrons), chlorine (17 electrons), and argon (18 electrons) are analogous in the electron configurations of their outer shells to their corresponding family members carbon, nitrogen, oxygen, fluorine, and neon, respectively, except that the principal quantum number of the outer shell of the heavier elements has increased by one to n = 3. [link] shows the lowest energy, or ground-state, electron configuration for these elements as well as that for atoms of each of the known elements.

A periodic table, entitled, “Electron Configuration Table” is shown. The table includes the outer electron configuration information, atomic numbers, and element symbols for all elements. A square for the element hydrogen is pulled out beneath the table to provide detail. The blue shaded square includes the atomic number in the upper left corner, which is 1, the element symbol, H in the upper right corner, and the outer electron configuration in the lower, central portion of the square. For H, this is 1 s superscript 1.
This version of the periodic table shows the outer-shell electron configuration of each element. Note that down each group, the configuration is often similar.

When we come to the next element in the periodic table, the alkali metal potassium (atomic number 19), we might expect that we would begin to add electrons to the 3 d subshell. However, all available chemical and physical evidence indicates that potassium is like lithium and sodium, and that the next electron is not added to the 3 d level but is, instead, added to the 4 s level ( [link] ). As discussed previously, the 3 d orbital with no radial nodes is higher in energy because it is less penetrating and more shielded from the nucleus than the 4 s , which has three radial nodes. Thus, potassium has an electron configuration of [Ar]4 s 1 . Hence, potassium corresponds to Li and Na in its valence shell configuration. The next electron is added to complete the 4 s subshell and calcium has an electron configuration of [Ar]4 s 2 . This gives calcium an outer-shell electron configuration corresponding to that of beryllium and magnesium.

Questions & Answers

to what volume must 8.32 NaOH be diluted to its analytical concentration 0.20 M
Sheriza Reply
weight in mg 1.76 mole of I
Sheriza
the types of hydrocarbons
Ohanaka Reply
u are mad go and open textbook
Emmanuel
hahahahahahahahahahahahaha
Jessica
aliphatic and aromatic hydrocarbons
Osakue
I don't use to see the messages
Adazion Reply
how can you determine the electronegativity of a compound or in molecules
Shalom Reply
when u move from left to right in a periodic table the negativity increases
reeza
Are you trying to say that the elctronegativity increases down the group and decreases across the period?
Ohanaka
yes and also increases across the period
reeza
for instance when you look at one group of elements in a periodic table electronegativity decreases when you go across the table electronegativity increases. hydrogen is more electronegative than sodium, potassium of that group. oxygen is more electronegative than carbon.
reeza
i hope we all know that organic compounds have carbon as their back bone
Madueke
OK,Thank you so much for the answer. I am happy now
Adazion Reply
can I ask you a question now
Osakue
yes
hanna
what is the oxidation number of nitrogen, oxygen and sulphur
Osakue
5, -2 & -2
hanna
What is an atom?
Adazion Reply
is a smallest particle of a chemical element that can exist
Osakue
can I ask a question
Osakue
it is a substance that cannot be broken down into simpler units by any chemical reaction
Madueke
An atom is the smallest part of an element dat can take part in chemical reaction.
Idris
an atom is the smallest part of an element that can take part in a chemical reaction nd still retain it chemical properties
Precious
what are the branches of an atomic mass
Adazion Reply
Still waiting for answers for a very long time now
Adazion
Please May una reply me ooo
Adazion
that question is very strong oooo
Osakue
most of the questions I asked wasn't answered what's the problem guys?
Adazion Reply
hi, there is no problems ooo
Osakue
between H2SO4 and HCL which is the strongest dehydrating agent ?
Ibirogba
HCl is the strongest dehydrating agent
Osakue
ᴡʜᴀᴛ ᴡɪʟʟ ᴏʙsᴇʀᴠᴇᴅ ɪғ ʟᴇᴀᴅ(ɪɪ)ɴɪᴛʀᴀᴛᴇs ɪs ᴀᴅᴅᴇᴅ ᴏɴ ᴛᴏ sᴏᴅɪᴜᴍ ɪᴏᴅɪᴅᴇ sᴏʟᴜᴛɪᴏɴ
Gawaar Reply
what is the functional group of alkanals
Frankyx Reply
can someone explain salt analysis properly
Frankyx
Find the number of calcium atoms present in a sample weighing 2.0*10 raise to the power of -3g
Mfoniso Reply
What does avogadro's law states?
Debora Reply
what is chemistry?
Adazion Reply
Is a branch of science that deals with matter in relation to energy
Kata
permanent hardness of water can be removed by ?
Okorie Reply
***watertreatmentbasics.com/temporary-and-permanent-hardness-of-water/
caco3
Owoyomi
ʜᴏᴡ
Gawaar
What are the basic area in in chemistry
John Reply
acid, base and salt
John
Why do people study chemistry
John
becuz chemistry is the study of elements, nature and etc
John
and also the study of matter and atom
John
is chemistry hard
Jojolade
the answer to that question depends on you
John
what kind of question are u asking fam?
Ibirogba
his asking if chemistry is hard
John
not really just a matter of you willing to study
Okorie
Practice Key Terms 7

Get the best Chemistry course in your pocket!





Source:  OpenStax, Chemistry. OpenStax CNX. May 20, 2015 Download for free at http://legacy.cnx.org/content/col11760/1.9
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Chemistry' conversation and receive update notifications?

Ask