The Atom
Electron Configurations
REVIEW
Indicate the location of each subatomic
particle on the atom shown below:
REVIEW
Which is the smallest?
Which has the smallest mass?
Which is unique for each atom?
REVIEW
The atomic number is equal to the
number of _____________ for an
atom.
The mass number is also known as the
_________________ and is equal to
the sum of the ____________ and the
______________.
REVIEW
A atom that has no charge is
considered to ________________.
In a neutral atom, the number of
_________________ equal the number
of electrons.
Electron Configurations
• The electron’s location is predicted and
expressed in terms of energy levels and
orbitals.
• Like all systems in nature, electrons
have arrangements that have the
lowest possible energy.
• Electrons occupy spaces called orbitals,
which in sub-levels, which are in an
energy level.
S orbital…each orbital has 2 e- max
P orbitals…each orbital has 2 e- max
D orbitals…each orbital has 2 e- max
F orbitals…each orbital has 2 e- max
Electrons will fill lowest energy levels first.
Notice that the 4s
fills before the
3d…why?
Write the e- Configuration of Calcium
• Step 1: Gather information
– Determine the atomic number of Ca.
• Step 2: Plan your work
– Atomic # = protons = electrons
• Step 3: Calculate
– Use filling order to write the configuration
– Answer:
• Step 4: Verify results
– Add up electrons, does it equal 20?
Write the e- Configuration of Nickel
• Step 1: Gather information
– Determine the atomic number of Ni
• Step 2: Plan your work
– Atomic # = protons = electrons
• Step 3: Calculate
– Use filling order to write the configuration
– Answer:
• Step 4: Verify results
– Add up electrons, does it equal 28?
Write the e- Configuration of Tin
• Step 1: Gather information
– Determine the atomic number of Sn
• Step 2: Plan your work
– Atomic # = protons = electrons
• Step 3: Calculate
– Use filling order to write the configuration
– Answer:
• Step 4: Verify results
– Add up electrons, does it equal 50?
Use the PT instead of energy diagram
Write the e- Configuration of Al
• Step 1: Gather information
– Determine the atomic number of Al
• Step 2: Plan your work
– Atomic # = protons = electrons
• Step 3: Calculate
– Use PT to write e- configuration
– Answer:
• Step 4: Verify results
– Add up electrons, does it equal 13?
Write the e- Configuration of Nitrogen
• Step 1: Gather information
– Determine the atomic number of N
• Step 2: Plan your work
– Atomic # = protons = electrons
• Step 3: Calculate
– Use PT to write e- configuration
– Answer:
• Step 4: Verify results
– Add up electrons, does it equal 7?
Short-Hand Version
•
•
•
•
Find the nearest noble gas
Put noble gas symbol in brackets
Finish configuration
Example:
– Na:
– Br:
Valence Electrons
• Outermost electrons
• Most important
– Are lost to form ions.
• Involved in chemical bonding
• Example:
– Na:
– Br: