Chemistry - Unit 1 - Atomic Structure

how to read and get info from the periodic table

Energy Shell/level(Schale)

A large, general region of space around the nucleus where an electron is likely to be found (like a neighborhood).

notation: 1, 2, 3, 4, etc.

higher number = further from the nucleus

Can hold up to:

First: 2 electrons

Second: 8

Third: 18

Fourth: 32

Subshell(Unterschale)

A region of space within an energy level where an electron is likely to be found (like a house within a neighborhood).

notation: s, p, d, f

always fill in order

Can hold up to:

s: 2 electrons

p: 6 (bc it has 3 orbitals)

d: 10 (bc 5 orbitals)

Orbital

A region of space within a subshellwhere an electron is likely to be found (like a room within a house).

There are:

1 of these in s

3 in p

5 in d

each holding up to 2 electrons only

Electron configuration

shows how many electrons are in each energy level for an element (separated by dashes "-" ).

ex.) S is 2-8-6 so:

in the 1st EL it has 2 electrons

in the 2nd EL it has 8 electrons

in the 3rd EL it has 6 electrons

To determine this on your own:

1. Find out how many electrons are in your element (Atomic Number)

2. Find out how many energy levels there are (Period)

2. Put the max amount of electrons in each EL separated by "-" until they run out (2-8-etc.).

Subshell configuration

shows exact location of electrons by specifying the:

energy level (1, 2, 3)

subshell (s, p, d) and

how many electrons are located in that subshell (¹, ², ³).

ex.) S is 1s²2²s2p⁴

Period 2 shows there are 2 ELs (1 & 2)

Atomic number says it has 6 valence electrons (notice in the 2nd EL there are ²+ ⁴ = 6 electrons)

Group

columns on the periodic

tell how many valence electrons are in an element

period (periode)

rows on the periodic table

tell how many energy levels are in an element

Valence electrons

electrons in the outermost energy level of an element (responsible for bonding and chemical properties)

known by looking at group number