Transcript of "Chapter 8.1: Electrons and Energy Levels"
Chapter 8.1: Electrons and Energy Levels - p266-272 – page1
Chemical bond (268) – a force that holds two or more atoms together
Valence Electron (270) – an outermost electron of an atom that participates in chemical
Electron Dot Diagram (271) – a model that represents valence electrons in an atom as dots
around the element’s chemical symbol
Periodic Table of Elements
o State of matter at room temperature
o Atomic (average) Mass
Periods and Groups
o ___________________ = Rows
o Groups = Columns
o Lists elements in order of atomic number
o Atomic number increases as you move from ________________ to _________________
o Elements in each group have similar chemical properties and react with other elements
in similar ways
Metals, Nonmetals, and Metalloids
Good __________________ of electricity and thermal energy
Easily pulled into wires and hammered into sheets
Have properties in common with both metals and ________________
Often used as semiconductors in electronic devices
Poor conductors of thermal energy and electricity
Most are _____________________at room temperature
Solid form tends to be brittle
o Pure elements are _____________________to find
o Atoms of different ____________________chemically combine and form compounds.
o Compounds make up all living and nonliving things
o Chemical ________________ hold together different elements in chemical compounds
o A chemical bond is a force that holds two or more atoms together
Chapter 8.1: Electrons and Energy Levels - p266-272 – page2
Electron Number and Arrangement
o The exact ___________________ of electrons in an atom cannot be
o Electrons are in constant _________________around the nucleus
o However, each electron is usually in a certain area of space around
o Some are in areas close to the nucleus, and some are in areas farther
Electrons and Energy
o Different electrons in an atom have different amounts of_____________.
o An electron moves around the nucleus at a _________________that
corresponds to its amount of energy
o Areas of space in which electrons move around the nucleus are called
o Electrons closet to the nucleus have the least amount of energy
They are at the _____________ lowest energy level
Only _____________ electrons can be in the lowest energy level
Electrons and Bonding
o Negatively charged electrons have an attraction to the _________________ charged
nucleus of an atom (like a magnet)
o The electrons in the energy levels closest to the
nucleus of the same atom have a
__________________attraction to that nucleus
o Electrons farther from that nucleus are
______________________ attracted to it.
o These outermost electrons can easily be attracted
to the nucleus of the other atoms
o This __________________ between the positive
nucleus of one atom and the negative electrons of
another is what causes a chemical bond.
o Electrons farthest from their nucleus are easily attracted to the nuclei of
o These outermost electrons are the only electrons that can form chemical bonds
This is because these electrons are exposed to the nuclei
of other atoms
o A __________________electron is an outermost electron of an
atom that participated in chemical bonding.
o Valence electrons have the most ____________________of all
electrons in an atom.
o The number of valence electrons in each atom of an element
can help determine the type and the number of
_______________ it can form.
o The periodic table can tell you how many valence electrons an
Chapter 8.1: Electrons and Energy Levels - p266-272 – page3
Except for Helium, elements in certain groups have the same number of valence
o In groups 1,2, 13-18, the number of valence electrons is shown by the ___________ digits
of the group.
o So, elements in group 18 have __________ valence electrons.
Electron Dot Diagrams
o In 1916, an America Chemist named Gilbert Lewis developed the electron dot diagram.
o The electron dot diagram is a model that represents __________________electrons in
an atom as dots around the element’s chemical symbol
o It can help you predict how an atom will ____________ with other atoms
o The dots represent the valence electron
o Some dots pair up, others do not
o The number of _________________dots is often the number of bonds an atom can
o See Figure 5, pg 271
- Draw the Lewis Dot Structure for the elements in the chart
o Remember that each element in a _________________ has the same number of valence
o SO, every element in a group has the same number of _________________ in its
electron dot diagram
o Atoms with 8 valence electrons do not easily react with other atoms
They are chemically stable
o Atoms that have 1-7 valence electrons are reactive of chemically unstable
They easily bond with other atoms and form chemically ____________
o Atoms of H and He have only one energy level
These atoms are chemically stable with _____________ valence electrons
o Elements in Group __________________ are called noble gases
o With the exception of He, noble gases have ______valence electrons and are chemically
Chapter 8.1: Electrons and Energy Levels - p266-272 – page4
o Chemically stable atoms do not easily____________________________, or form bonds,
with other atoms
Stable and Unstable Atoms
o Atoms with unpaired dots in their electron dot diagram are reactive, or chemically
o For example, N has 5 valence electrons are ______________ of them are unpaired.
o It is reactive and will become more stable by forming chemical bonds with other atoms
o When an atom forms a bond, it__________________, loses, or shares valence electrons
with other atoms.
o By forming bonds, atoms become more chemically stable