atomic size, ionization energy, & electronegativity 1.c. – students know how to use the...
TRANSCRIPT
Atomic Size, Ionization Energy, & Electronegativity
1.c. – Students know how to use the periodic table to identify alkali metals, alkaline earth metals and transition metals, trends in ionization
energy, electronegativity, and the relative sizes of ions and atoms.
PERIODIC TABLE TRENDS
PERIODIC LAW
• Mendeleev understood the ‘Periodic Law’ which states:
“WHEN ARRANGED BY INCREASING ATOMIC NUMBER, THE CHEMICAL
ELEMENTS DISPLAY A REGULAR AND REPEATING PATTERN OF CHEMICAL
AND PHYSICAL PROPERTIES”.
• Atoms with similar properties appear in groups or families (vertical columns) on the periodic table.
• They are similar because they all have the same number of valence (outer shell) electrons, which governs their chemical behavior.
PERIODIC LAW CONTINUE
Families or Groups share similar chemical and physical
properties!
Are Elements in a Row or Period Alike?
• There are several other important atomic characteristics that show predictable trends that you should know.
1. Atomic size2. Ionization Energy3. Electronegativity
PERIODIC LAW CONTINUE
• Atoms on the left side of the periodic table are bigger than atoms on the right side of the periodic table.
• As we move across a period….protons are added….this increases the nuclear charge (+)!
• As protons are added….electrons are also added….so the electrostatic attraction increases (positive & negative attraction)!
• This attraction pulls the outermost electrons in closer to the nucleus….making the atom smaller!
+ _+ _
Na Mg Al Si P S Cl Ar
• Atomic size tends to increase from right to left and from top to bottom.
Atomic Size Increases
Atom
ic S
ize
Incr
ease
s
• Ionization Energy - amount of energy needed to remove an electron from an atom.
IONIZATION ENERGY
Is it harder to take electrons from elements
that want to lose e- or
elements that wants to gain
e-?
• It is harder to remove an electron from smaller atoms because the nucleus is closer and better able to hold on to them.
• It is easier to take electrons from larger atoms because the electrons are further from the nucleus.
• It is easier to take electrons from metals since they want to LOSE electrons!
Alkali
metal HalogensNoble Gases
LOW IONIZATION
ENERGY
Medium-High IONIZATION
ENERGY
Very High IONIZATION
ENERGY
• It is easier for small atoms to attract an electron because the nucleus is closer and is better able to hold on to them.
• It is easier for nonmetals to gain electrons.
Which element has the highest
electronegativity?
Putting It All TogetherMetals Metalloids
(Semimetals)Nonmetals
Left SideAlkali Alkaline Earth Transition
Elements dividing the metals and nonmetals (stair-step line)
Right SideHalogensNoble Gases
Give up (Lose) e-Cations
Give up (Lose) e- Or Accept (Gain) e-
Accept (Gain) e-
Anions
Big Atomic Size Small Atomic Size
Low Ionization High Ionization
Low Electronegativity High Electronegativity(Excluding Noble Gases)
(Noble gases do not gain e-)
Cornell Questions• As you move across a Period, how does the
atomic number change?• As you move across a Period, how does the “pull”
of the nucleus on the electrons change?• As you move across a Period, how does the
atomic size, ionization energy, and electronegativity change?
• As you move down a Group, how does the atomic size, ionization energy, and electronegativity change?
Create a Periodic Table Trends Periodic Table
1. Number the rows and groups2. Draw increasing arrows representing atomic
size (must be in color)3. Draw increasing arrows representing
ionization energy (must be in a different color)
4. Draw increasing arrows representing electronegativity (must be in a different color)