1. Ch. 14 Notes---Chemical Periodicity
Valence Electrons and Electron Dot Notations
What are “valence electrons”?
These are the electrons in the _________-_______ energy level (or shell).
They will be “___” electrons and “___” electrons only.
Counting Valence Electrons
Group A # = number of valence electrons
(only exception Helium = __ e-’s)
Examples: Ca = __ e-’s Nitrogen = __ e-’s Argon = __ e-’s
d-block and f-block = ___valence e-’s
outer
most p s 2 2 5 8 2

2. Drawing Valence Electrons
“Electron-dot notation”: Electrons will be represented as dots located around the symbol of the element in the pattern shown below.
Examples: Nitrogen = Hydrogen =
(important exception.... Carbon = ) X 3 6 4 1 7 2 5 8 N H C

3. The Development of the Periodic Table
Dmitri Mendeleev
_________________________: constructed the 1st periodic table
Features of Mendeleev’s Periodic Table
(See p.390)
He left ______ _________ for “missing elements”. Later when these elements were discovered, he filled in the gaps.
He arranged the elements in columns and rows according to their __________________. Elements with similar properties were in the same horizontal row.
He was able to accurately ___________ the properties of the missing elements based on the properties of the elements in similar _______.
He ordered the elements by increasing __________ ___________.
blank spaces
properties
predict
columns
atomic mass

4. Features of the Modern Periodic Table (See Fig. 14.2)
In 1913, Henry ______________ determined the atomic number, (# of ___), of the elements.
He then arranged the elements in the periodic table by increasing atomic ____________.
This switched the position of some elements. This is how the modern periodic table is arranged today.
Horizontal Rows = ____________ or Series
Vertical Columns = ____________ or Families
Elements in the same _________/_________ have similar properties.
Moseley p+
number
Periods
Groups
groups
families

5. Parts of the Periodic Table
Metals: located to the _______ of the dark zig-zag line running through the “p-block”. This includes the elements in the ___-block.
Properties of Metals
shiny surface
______________ (you can pound it into a flat sheet)
______________ (you can draw it into a thin wire)
good _______________ (heat/electricity travels through it easily)
left f
malleable
ductile
conductors

6. Parts of the Periodic Table
Nonmetals: located to the ___________ of the dark zig-zag line.
Properties of Nonmetals
_______ surface
______________
good _______________ (or poor conductors)
Metalliods: located on the border of the dark zig-zag line.
Examples: Silicon & Germanium
Properties of Metalliods
___________________
right
dull
sulfur
brittle
insulators
semiconductors
(Used in computer chips)

7. Parts of the Periodic Table
d-block metals: “_________________ metals”
f-block metals: “Inner-transition metals” or “____________ metals”
Special Group/Family Names
Group 1: “_________ metals”
React with _________ to form a base
Group 2: “________________ metals”
Compounds are used in batteries
Group 17: “_________________”
Used in some light fixtures
Group 18 (or 0 or 18): “_______ gases”
Don’t form compounds (_________)
transition
rare-earth
Alkali
water
Alkaline-earth
Halogens
Noble
inert

8. Trends in the Periodic Table
Atomic Size (Atomic Radius)
(See Fig )
Moving Down a Group= the size of the atoms ________________
Why? You are adding ________ of electrons to higher and higher energy levels (farther and farther out.)
Moving Across a Period= the size generally ______________
Why? You are adding more e- and p+ to the same energy level. This causes more ______________ of opposite charges and it __________ the electron cloud inward.
increases
more
decreases
attraction
pulls

9. Trends in the Periodic Table
Atomic Size vs. Ion Size
(See Fig. 14.8)
Cation = (___) charged atom created by ___________ e-’s.
Cations are ______________ than the original atom.
_____________ generally form cations.
Anion = (___) charged atom created by _____________ e-’s.
Anions are ____________ than the original atom.
_______________ generally form anions. +
removing
smaller
Metals −
adding
larger
Nonmetals

10. Trends in the Periodic Table
Atomic Size vs. Ion Size

11. Trends in the Periodic Table
Ionization Energy
(See Table 14.1 & Fig )
Ionization energy is the energy required to _______________ the outer most electron in an atom.
Moving Down a Group= _______________ (less energy is needed)
Why? You are trying to remove an electron that is farther and farther out (for larger and larger atoms). These e-’s are not as ________________to the nucleus.
In general, the larger the atom, the ____ attracted it is to its e-’s.
remove
decreases
attracted
less

12. Trends in the Periodic Table
Ionization Energy
Moving Across a Period= generally ________________
Why? Moving across a period takes us from metals to nonmetals. More ionization energy is needed for ______________ compared to __________.
Also, since metals generally form _________, it won’t take as much energy to remove it’s outer most electron.
Remember that as you move across the period, the atoms get _________ and therefore ______ attracted to the electrons.
increases
nonmetals
metals
cations
smaller
more

13. Trends in the Periodic Table
“Successive Ionization Energies”
(See Table 14.1)
“Successive Ionization Energies” means the energy required to remove a _____ or a _____ electron from an atom.
Removing more and more e-’s requires ______ and ______ energy.
Why? The remaining e-’s are more _________ _________ to the nucleus.
2nd
3rd
more more
tightly bound

14. Trends in the Periodic Table
Electronegativity
(See Table 14.2)
Electronegativity is a relative value (from_________) which compares how much an atom is attracted to the e-’s in a ____________ bond.
Moving Down a Group= generally ______________ (less attraction)
Why? The bonded electron is farther and farther out. These e-’s will not be as attracted to the larger and larger atoms.
0 – 4.0
chemical
decreases

15. Trends in the Periodic Table
Electronegativity
Moving Across a Period= generally _________________
Why? Again, the atoms are getting ________ so they are _______ attracted to the bonding electrons.
Also, moving across a period takes us from metals to nonmetals. Since nonmetals generally form _________, they tend to __________ e-’s anyway, and this makes them ________________ attracted to e-’s when forming a chemical bond.
___________ __________ are not listed in Table 14.2 since they do not ________ _____________ !
increases
smaller
more
anions
gain
highly
Noble gases
form compounds

16. Determining the Ion Formed
Atoms try to achieve a ________ ______ configuration when forming an ion. (This makes them more stable.)
Locate the nearest noble gas and count how many “places” it is away, but remember that you can skip over the d-block!!
This amount will be the same as the # of e-’s either gained or lost by the atom when forming an ion.
Practice Problem: How many electrons are gained or lost when forming an ion from the following elements?
a) Magnesium: ____ (gained or lost) b) Iodine: ____ (gained or lost)
c) Gallium:____ (gained or lost) d) Boron:____ (gained or lost)
noble gas 2 1 3 3