1. Section 3 Trends and the Periodic Table
Chapter 5
Section 3
Trends and the Periodic Table

2. Valence Electrons
______________: the electrons available to be lost, gained, or shared in the formation of _____________________
Usually, _________energy level
Valence electrons are often located in ____________filled main-energy levels
Groups 1 and 2 have ________valence electrons, groups have _________ __________________________________

3. ALL Periodic Table Trends
Influenced by three factors:
1. _________________
Higher energy levels are further away from the nucleus.
____________________________
2. ______________________(protons)
More charge pulls electrons in closer. (+ and – attract each other)

4. Shielding
The electron on the ________energy level has to “look through” all the other energy levels to see the nucleus.
It is “__________”.
A different electron has ______shielding, if it is in the __________

5. What do they influence?
____________and ________ have an effect on the GROUP (  )
___________has an effect on a PERIOD (  )

6. ______________- Group trendsH
As we go ______a group). . .
each atom has an _________energy level,
so the atomic radii (size) _________ Li Na K Rb

7. _____________- Period Trends
Going from left to right across a period, the atomic size ____________.
Electrons are in the ________________.
But, there is more _______________.
Outermost electrons are pulled _________. Na Mg Al Si P S Cl Ar

8. Rb K
Period 2 Na Li
Atomic Radius (pm) Kr Ar Ne H 3 10
Atomic Number

9. Ions Some compounds are composed of particles called “________”
An ______is an atom (or group of atoms) that has a ________________________
________are neutral because the number of protons equals electrons
Positive and negative ions are formed when electrons are ____________(lost or gained) between atoms
_______and ________are no longer equal

10. ___________________, from their outer energy level
Ions
___________________, from their outer energy level
Sodium loses one: there are now more protons (11) than electrons (10), and thus a positively charged particle is formed = “___________”
The charge is written as a number followed by a plus sign: Na1+
Now named a “_____________”

11. ____________________one or more electrons
Ions
____________________one or more electrons
Chlorine will gain one ___________
Protons (17) no longer equals the electrons (18), so a charge of -1
Cl1- is re-named a “chloride ion”
Negative ions are called “_________”

12. Trends in Ionic Size: Cations
Cations form by ___________electrons.
Cations are ________than the ______atom – not only do they lose electrons, they can lose an entire energy level.
________generally form cations.
Cations of __________________elements achieve the electron configuration of the noble gas ______________them.

13. Ionic size: Anions Anions form by __________electrons.
Anions are _______than the atom they came from – have the same energy level, but a reduced _______ nuclear charge.
________________form anions.
Anions of _______________elements achieve an electron configuration like the ___________that ________them.

14. Configuration of Ions
_______often have noble gas configurations (a _______outer level)
Na atom is: ________________
Forms a 1+ sodium ion: ___________
Same configuration as _________.

15. Size of Isoelectronic ions
Iso- means “the ________”
Isoelectronic ions have the same # of ______________
Al3+ Mg2+ Na1+ Ne F1- O2- and N3-
all have _____electrons
all have the same configuration: _________(which is the noble gas: ____)

16. Driving Forces
________________require lots of energy to remove their ________.
_____________have full orbitals.
Atoms behave in ways to try and achieve an __________________ that is like a _____________.

17. Trends in Ionization Energy
_________________is the amount of energy required to completely ____________ an electron (from a gaseous atom).
Removing one electron makes a 1+ ion.
The energy required to remove only the ______outer electron is called the ________________________.

18. Ionization Energy
The ________ionization energy is the energy required to remove the __________electron.
Always ___________than first IE.
The ______IE is the energy required to remove a ___________electron.
_____________than 1st or 2nd IE.

19. Symbol First Second Third
HHeLiBeBCNO F Ne
Why did these values increase so much?

20. What factors determine IE
The ________the nuclear charge, the ______________IE.
_____________distance from nucleus _________________IE
Shielding effect = lower IE
_______and _________orbitals have ______potential energy, so achieving them is easier. This means _____IE.

21. Ionization Energy - Group trends
As you go _________a group, the first IE ______ because...
The electron is ________away from the attraction of the nucleus, and there is more _______________.

22. Ionization Energy - Period trends
All the atoms in the _________period have the ________energy level (Same shielding.)
But, ____________nuclear charge
So IE generally ____________from left to right.
Exceptions at ____and _____orbitals.

23. First Ionization energy
Atomic number

24. Trends in Electronegativity
_______________is the tendency for an atom to __________electrons to itself when it is covalently bonded with another element.
They share the electron, but how equally do they share it?
An element with a __________ electronegativity means it pulls the electron towards itself ___________.

25. Electronegativity Group Trend
The farther _________a group, the farther the electron is away from the _______. There is also more __________occurring.
Attraction for that electron is ______so low _____________.
Going ________the group, electronegativity __________.

26. Electronegativity Period Trend
_______are at the _____of the table and they let their electrons go ____
Thus, low _______________
On the ____side are the _________. They want _____electrons and try to take them from other ________.
Going __________the period, electronegativity ______________.
Think back to _________________.

27. Trend: ___________(and ionic size) decrease going across the period and increase going down a group:

28. Trend: ___________________ and _______________increase going across the period and increase going up a group