periodic trends
DESCRIPTION
Periodic Trends. OBJECTIVES: Interpret group trends in atomic radii, ionic radii, ionization energies, m.p., b.p., electronegativity and chemical properties. Trends in Atomic Size. First problem: Where do you start measuring from? The electron cloud doesn’t have a definite edge. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/1.jpg)
Periodic Trends
OBJECTIVES:
• Interpret group trends in atomic radii, ionic radii, ionization energies, m.p., b.p., electronegativity and chemical properties
![Page 2: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/2.jpg)
Trends in Atomic Size First problem: Where do you
start measuring from? The electron cloud doesn’t have
a definite edge. They get around this by
measuring more than 1 atom at a time.
![Page 3: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/3.jpg)
Atomic Size
Atomic Radius = half the distance between two nuclei of a diatomic molecule.
}Radius
![Page 4: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/4.jpg)
Trends in Atomic Size Influenced by three factors:
1. Energy Level
• Higher energy level is further away.
2. Charge on nucleus
• More charge pulls electrons in closer.
3. Shielding effect e <-> e repulsion
![Page 5: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/5.jpg)
Group trends As we go down
a group... each atom has
another energy level,
so the atoms get bigger.
HLi
Na
K
Rb
![Page 6: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/6.jpg)
Periodic Trends As you go across a period, the
radius gets smaller. Electrons are in same energy level. More nuclear charge. Outermost electrons are closer.
Na Mg Al Si P S Cl Ar
![Page 7: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/7.jpg)
Overall
Atomic Number
Ato
mic
Rad
ius
(nm
)
H
Li
Ne
Ar
10
Na
K
Kr
Rb
![Page 8: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/8.jpg)
Trends in Ionization Energy
The amount of energy required to completely remove a mole of electrons from a mole of gaseous atoms.
Removing an electron makes a +1 ion.
The energy required to remove (1 mole of) the first electron is called the first ionization energy.
![Page 9: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/9.jpg)
Ionization Energy The second ionization energy is
the energy required to remove (1 mole of) the second electron(s).
Always greater than first IE. The third IE is the energy
required to remove a third electron.
Greater than 1st or 2nd IE.
![Page 10: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/10.jpg)
Symbol First Second ThirdHHeLiBeBCNO F Ne
1312 2731 520 900 800 1086 1402 1314 1681 2080
5247 7297 1757 2430 2352 2857 3391 3375 3963
11810 14840 3569 4619 4577 5301 6045 6276
![Page 11: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/11.jpg)
Symbol First Second ThirdHHeLiBeBCNO F Ne
1312 2731 520 900 800 1086 1402 1314 1681 2080
5247 7297 1757 2430 2352 2857 3391 3375 3963
11810 14840 3569 4619 4577 5301 6045 6276
![Page 12: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/12.jpg)
What determines IE The greater the nuclear charge,
the greater IE. Greater distance from nucleus
decreases IE Filled and half-filled orbitals have
lower energy, so achieving them is easier, lower IE.
Shielding effect
![Page 13: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/13.jpg)
Shielding The electron in the
outermost energy level experiences more inter-electron repulsion (shielding).
Second electron has same shielding, if it is in the same period
![Page 14: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/14.jpg)
Group trends As you go down a group, first IE
decreases because... The electron is further away. More shielding.
![Page 15: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/15.jpg)
Periodic trends All the atoms in the same period
have the same energy level. Same shielding. But, increasing nuclear charge So IE generally increases from
left to right. Exceptions at full and 1/2 full
orbitals.
![Page 16: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/16.jpg)
Firs
t Ion
izat
ion
ener
gy
Atomic number
He
He has a greater IE than H.
same shielding greater nuclear
charge
H
![Page 17: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/17.jpg)
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li has lower IE than H
Outer electron further away
outweighs greater nuclear charge
Li
![Page 18: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/18.jpg)
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Be has higher IE than Li
same shielding greater nuclear
charge
Li
Be
![Page 19: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/19.jpg)
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He B has lower IE
than Be same shielding greater nuclear
charge p orbital is slightly
more diffuse and its electron easier to remove
Li
Be
B
![Page 20: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/20.jpg)
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
![Page 21: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/21.jpg)
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
![Page 22: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/22.jpg)
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
O
Breaks the pattern, because the outer electron is paired in a p orbital and experiences inter-electron repulsion.
![Page 23: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/23.jpg)
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
O
F
![Page 24: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/24.jpg)
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
O
F
Ne Ne has a lower
IE than He Both are full, Ne has more
shielding Greater
distance
![Page 25: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/25.jpg)
Firs
t Ion
izat
ion
ener
gy
Atomic number
H
He
Li
Be
B
C
N
O
F
Ne Na has a lower
IE than Li Both are s1
Na has more shielding
Greater distance
Na
![Page 26: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/26.jpg)
Firs
t Ion
izat
ion
ener
gy
Atomic number
![Page 27: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/27.jpg)
Driving Force Full Energy Levels require lots of
energy to remove their electrons. Noble Gases have full orbitals. Atoms behave in ways to
achieve noble gas configuration.
![Page 28: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/28.jpg)
Trends in Electron Affinity The energy change associated with
adding an electron (mole of electrons) to a (mole of) gaseous atom(s).
Easiest to add to group 7A. Gets them to full energy level. Increase from left to right: atoms
become smaller, with greater nuclear charge.
Decrease as we go down a group.
![Page 29: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/29.jpg)
Trends in Ionic Size Cations form by losing electrons. Cations are smaller that the atom
they come from. Metals form cations. Cations of representative
elements have noble gas configuration.
![Page 30: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/30.jpg)
Ionic size Anions form by gaining
electrons. Anions are bigger that the atom
they come from. Nonmetals form anions. Anions of ‘A’ groups elements
have noble gas configuration.
![Page 31: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/31.jpg)
Configuration of Ions Ions have noble gas configurations
(not transition metals). Na is: 1s22s22p63s1 Forms a 1+ ion: 1s22s22p6 Same configuration as neon. Metals form ions with the
configuration of the noble gas before them - they lose electrons.
![Page 32: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/32.jpg)
Configuration of Ions Non-metals form ions by gaining
electrons to achieve noble gas configuration.
They end up with the configuration of the noble gas after them.
![Page 33: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/33.jpg)
Group trends Adding energy level Ions get bigger as
you go down.
Li1+
Na1+
K1+
Rb1+
Cs1+
![Page 34: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/34.jpg)
Periodic Trends Across the period, nuclear charge
increases so they get smaller. Energy level changes between
anions and cations.
Li1+
Be2+
B3+
C4+
N3-O2- F1-
![Page 35: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/35.jpg)
Size of Isoelectronic ions Iso- means the same Iso electronic ions have the
same # of electrons Al3+ Mg2+ Na1+ Ne F1- O2- and N3- all have 10 electrons all have the configuration:
1s22s22p6
![Page 36: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/36.jpg)
Size of Isoelectronic ions Positive ions that have more
protons would be smaller.
Al3+
Mg2+
Na1+ Ne F1- O2- N3-
![Page 37: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/37.jpg)
Electronegativity The tendency for an atom to attract
electrons to itself when it is chemically combined with another element.
High electronegativity means it pulls the electron toward it.
Atoms with large negative electron affinity have larger electronegativity.
![Page 38: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/38.jpg)
Group Trend The further down a group, the
farther the electron is away, and the more electrons an atom has.
More willing to share. Low electronegativity.
![Page 39: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/39.jpg)
Periodic Trend Metals are at the left of the table. They let their electrons go easily Low electronegativity At the right end are the
nonmetals. They want more electrons. Try to take them away from others High electronegativity.
![Page 40: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/40.jpg)
Ionization energy, Electronegativity, and Electron Affinity INCREASE
![Page 41: Periodic Trends](https://reader031.vdocuments.mx/reader031/viewer/2022012916/56812ca9550346895d915598/html5/thumbnails/41.jpg)
Atomic size increases, shielding constant
Ionic size increases