Periodic Table and Trends

Сентябрь 9, 2022

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Periodic Table and Trends

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2. History of the Periodic Table 1871 – Mendeleev arranged the elements according to: 1. Increasing atomic
3. Group Names
4. S & P block – Representative Elements Metalloids (Semimetals, Semiconductors) – B,Si, Ge, As, Sb, Te
5. Periodic Groups Elements in the same column have similar chemical and physical properties These similarities are
6. Periodic Trends Periodic Trends – patterns (don’t always hold true) can be seen with our current
7. Atomic Radius Atomic Radius – size of an atom (distance from nucleus to outermost e-)
8. Atomic Radius Trend Group Trend – As you go down a column, atomic radius increases As
9. Ionic Radius Ionic Radius – size of an atom when it is an ion
10. Ionic Radius Trend Metals – lose e-, which means more p+ than e- (more attraction) SO…
11. Ionic Radius Trend Group Trend – As you go down a column, ionic radius increases Periodic
12. Ionic Radius
13. Ionic Radius How do I remember this????? The more electrons that are lost, the greater the
14. Ionic Radius How do I remember this??? The more electrons that are gained, the greater the
15. Ionization Energy Ionization Energy – energy needed to remove outermost e-
16. Ionization Energy Group Trend – As you go down a column, ionization energy decreases As you
17. Electronegativity Electronegativity- tendency of an atom to attract e-
18. Electronegativity Trend Group Trend – As you go down a column, electronegativity decreases As you go
19. Reactivity Reactivity – tendency of an atom to react Metals – lose e- when they react,
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History of the Periodic Table
1871 – Mendeleev arranged the elements according

to: 1. Increasing atomic mass 2. Elements w/ similar properties were put in the same row
1913 – Moseley arranged the elements according to: 1. Increasing atomic number 2. Elements w/ similar properties were put in the same column

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Group Names

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S & P block – Representative Elements
Metalloids (Semimetals, Semiconductors) – B,Si,

Ge, As, Sb, Te (properties of both metals & nonmetals)
Columns – groups or families Rows - periods

METALS

TRANSITION METALS

NONMETALS

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Periodic Groups
Elements in the same column have similar chemical and physical

properties
These similarities are observed because elements in a column have similar e- configurations (same amount of electrons in outermost shell)

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Periodic Trends
Periodic Trends – patterns (don’t always hold true) can be

seen with our current arrangement of the elements (Moseley)
Trends we’ll be looking at:
Atomic Radius
Ionization Energy
3. Electronegativity

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Atomic Radius
Atomic Radius – size of an atom
(distance from

nucleus to outermost e-)

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Atomic Radius Trend
Group Trend – As you go down a column,

atomic radius increases
As you go down, e- are filled into orbitals that are farther away from the nucleus (attraction not as strong)
Periodic Trend – As you go across a period (L to R), atomic radius decreases
As you go L to R, e- are put into the same orbital, but more p+ and e- total (more attraction = smaller size)

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Ionic Radius
Ionic Radius –
size of an atom when it

is an ion

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Ionic Radius Trend
Metals – lose e-, which means more p+ than

e- (more attraction) SO…
Cation Radius < Neutral Atomic Radius
Nonmetals – gain e-, which means more e- than p+ (not as much attraction) SO…
Anion Radius > Neutral Atomic Radius

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Ionic Radius Trend
Group Trend – As you go down a column,

ionic radius increases
Periodic Trend – As you go across a period (L to R), cation radius decreases,
anion radius decreases, too.
As you go L to R, cations have more attraction (smaller size because more p+ than e-). The anions have a larger size than the cations, but also decrease L to R because of less attraction (more e- than p+)

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Ionic Radius

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Ionic Radius
How do I remember this?????
The more electrons that are lost,

the greater the reduction in size.
Li+1 Be+2
protons 3 protons 4
electrons 2 electrons 2
Which ion is smaller?

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Ionic Radius
How do I remember this???
The more electrons that are gained,

the greater the increase in size.
P-3 S-2
protons 15 protons 16
electrons 18 electrons 18
Which ion is smaller?

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Ionization Energy
Ionization Energy – energy needed to remove outermost e-

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Ionization Energy
Group Trend – As you go down a column, ionization

energy decreases
As you go down, atomic size is increasing (less attraction), so easier to remove an e-
Periodic Trend – As you go across a period (L to R), ionization energy increases
As you go L to R, atomic size is decreasing (more attraction), so more difficult to remove an e-
(also, metals want to lose e-, but nonmetals do not)

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Electronegativity
Electronegativity- tendency of an atom to attract e-

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Electronegativity Trend
Group Trend – As you go down a column, electronegativity

decreases
As you go down, atomic size is increasing, so less attraction to its own e- and other atom’s e-
Periodic Trend – As you go across a period (L to R), electronegativity increases
As you go L to R, atomic size is decreasing, so there is more attraction to its own e- and other atom’s e-

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Reactivity
Reactivity – tendency of an atom to react
Metals – lose e-

when they react, so metals’ reactivity is based on lowest Ionization Energy (bottom/left corner) Low I.E = High Reactivity
Nonmetals – gain e- when they react, so nonmetals’ reactivity is based on high electronegativity (upper/right corner)
High electronegativity = High reactivity