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Unit 8 Periodic Trends. Textbook chapter 5 http:// www.youtube.com /user/ Hermcast. 5.1 HISTORY OF THE PERIODIC TABLE. Brainstorm some possible ways to organize the about 70 elements known by the mid-1800s. 5.1 HISTORY OF THE PERIODIC TABLE.

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unit 8 periodic trends

Unit 8 Periodic Trends

Textbook chapter 5

http://www.youtube.com/user/Hermcast

5 1 history of the periodic table
5.1 HISTORY OF THE PERIODIC TABLE
  • Brainstorm some possible ways to organize the about 70 elements known by the mid-1800s.
5 1 history of the periodic table1
5.1 HISTORY OF THE PERIODIC TABLE
  • Brainstorm some possible ways to organize the about 70 elements known by the mid-1800s.
  • Alphabetic
  • Physical states
slide4

1817 Johann Döbereiner’s. Organized elements into ______triads_____, similar to atomic __family_ or groups.

http en wikipedia org wiki johann wolfgang d c3 b6bereiner
http://en.wikipedia.org/wiki/Johann_Wolfgang_D%C3%B6bereiner
  • For example, the average atomic mass of lithium and potassium was close to the atomic mass of sodium. A similar pattern was found with calcium, strontium, and barium, with sulphur, selenium, and tellurium, and also with chlorine, bromine, and iodine.
  • http://www.merriam-webster.com/cgi-bin/audio-medlineplus.pl?bixdob01=Dobereiner
slide6

1863 John Newlands. Arranged elements in order of increasing atomic masses. Noticed a pattern formed by every 8th element, called it the “Law of octaves”. Remember, at this time the entire ___noble gas__ family was unknown.

slide7

1869 Dmitri Mendeleev, know as the “The father of the periodic table__”. Agreed with Newlands’ arrangement, but added transitions, giving the periodic table its current shape.

slide9

Left blank spots on the chart for adding in as yet undiscovered elements.

  • Made predictions about the chemical and physical properties of these elements. His most famous example of this is regarding Ekasilicon, or modern day Germanium.
mendeleev s periodic law states
Mendeleev’s Periodic Law states:
  • “The physical and chemical properties of elements are periodic functions of their atomic mass."
slide12

The main value of the periodic table is the ability to predict the chemical properties of an element based on its location on the table. It should be noted that the properties vary differently when moving vertically along the columns of the table than when moving horizontally along the rows.

slide13

Lothar Meyer 1869. Worked on the periodic table independent of Mendeleev and came to the same conclusions. Didn’t add predictions and so didn’t get the credit.

slide14

1911 Henry Moseley Noticed 3 pairs of elements out of place. They are:__________, _____________, and _____________. Restated the Periodic Law as :

slide15

1911 Henry Moseley Noticed 3 pairs of elements out of place. They are: Te + I, Co + Ni, and Ar + K. Restated the Periodic Law as :

  • “The physical and chemical properties of elements are periodic functions of their atomic number."
5 2 electron configurations and the periodic table
5.2 Electron Configurations and the Periodic Table
  • Periods and Blocks of the Periodic Table
  • “s” Block = groups # __1 ______ and ______2_______
  •   s = sharp
  • “p” Block = groups # __13__________ thru ____18______
  •   p = principal
  • “d” Block = groups # ____3_______ thru ______12_____
  •   d = diffuse
  • “f” Block = groups # Lanthanide and Actinide
  •   f = fundamental
5 3 electron configuration and periodic properties
5.3 Electron Configuration and Periodic Properties
  • Atomic radii is defined as: The distance between nuclei of 2 atoms.
need a blank sheet of paper
Need a blank sheet of paper
  • Draw:
  • Li Be B C N O F Ne
  • Na
  • K
  • Rb

See hermcast for an added explanation

trends for atomic size
TRENDS for atomic size:
  • Group: Atomic size ___________ as you move up a group.
  • Period: Atomic size________ as you move left to right across a period.
on back of blank sheet of paper
On back of blank sheet of paper
  • Atomic size:

Periodic Table

See hermcast for an added explanation

slide22

Shielding effect explanation: For elements with several electrons arranged over several shells (energy levels), inner electrons block (or shield) outer or valance electrons from the positive charge of the nucleus.

slide23

Shielding effect explanation: For elements with several electrons arranged over several shells (energy levels), inner electrons block (or shield) outer or valance electrons from the positive charge of the nucleus. This causes a decrease in charge attractions, making the outer electrons easier to lose.

1 atomic radii p150
1. Atomic Radii (p150)
  • periodic trend (left to right)– decreases
    • due to increasing charge of the nucleus
      • Why does charge increase?
  • group trend (top to bottom)– increases
    • due to shielding by other electrons
      • What is shielding?
1 atomic radii p1501
1. Atomic Radii (p150)
  • periodic trend (left to right)– decreases
    • due to increasing charge of the nucleus
      • Why does charge increase?
        • As you move from left to right the number of protons increase
        • Since there are more protons in the nucleus and they all have a positive charge they pull the electrons moving around them closer to the nucleus this makes the elements on the right smaller than the elements on the left.
1 atomic radii p1502
1. Atomic Radii (p150)
  • group trend (top to bottom)– increases
    • due to shielding by other electrons
      • What is shielding?
        • As you move down a group the size of atoms increase because you are adding energy levels
        • Energy levels are the areas electrons are moving around the nucleus.
        • Since electrons don’t want to be near each other since the are the same charge there is a large gap between energy levels
        • This makes the atoms larger as you move down
periodic trends in ionization energy a energy a e
Periodic Trends in Ionization EnergyA + Energy  A+ + e-
  • Ionization Energy is the amount of energy needed to lose an electron. This causes the atomic to become an ion.
periodic trends in ionization energy a energy a e1
Periodic Trends in Ionization EnergyA + Energy  A+ + e-
  • Ionization Energy is the amount of energy needed to lose an electron. This causes the atomic to become an ion.
  • Metals tend to form cations, low ionization energy value.
slide31

Nonmetals hate forming cations, instead prefer to form anions. They have a high ionization energy.

slide32

First ionization Energy is the amount needed to remove the _first___ electron.

  • Second ionization Energy is the amount needed to remove the __second__ electron.
  • Third ionization Energy is the amount needed to remove the __third__ electron.
trends in ionization energy
TRENDS in ionization energy:
  • Group: Tends to increase as you move up a group.
  • Period: Tends to increase as you move left to right across a period.
  • Highest ionization energy?
  • Lowest?
on back of blank sheet of paper1
On back of blank sheet of paper
  • Ionization energy:

Periodic Table

See hermcast for an added explanation

2 ionization energy p154
2. Ionization energy (p154)
  • element + energy  Element+ + e-
  • def- energy required to remove one electron from a neutral atom (first ionization energy)
  • periodic trend – increases
    • due to the electrons become closer to the nucleus
  • group trends – decreases
    • due to shielding
2 ionization energy p1541
2. Ionization energy (p154)
  • element + energy  Element+ + e-
  • def- energy required to remove one electron from a neutral atom (first ionization energy)
  • periodic trend – increases
    • due to the electrons become closer to the nucleus
      • This holds the electrons more strongly than if the electrons were further apart
      • Since they are held on more strongly it takes more energy to pull them off and remove them
      • Therefore there is a larger number associated with energy
2 ionization energy p1542
2. Ionization energy (p154)
  • H + energy  H+ + e-
  • group trends – decreases
    • due to shielding
      • It’s easier to pull electrons off since they are further away from the nucleus.
      • They are further away since as you move down there are move energy levels
slide39

second ionization energy – removal of a second electron (this requires more energy)

    • Why does it require more energy?
    • Once you remove one electron now you have a positively charged ion
      • Na  Na+ +e-
      • Na+ is already positively charge trying to make it Na+2 requires A LOT of energy
  • once you remove enough electrons to achieve an electron configuration of a noble gas it is very difficult to remove an additional electron (requires a LOT of energy)
electron affinity a e a energy
Electron Affinity A + e- A- + Energy
  • Electron affinity: a measure of the attraction an atom has for gaining electrons.
  • An affinity is an attraction for something.
feel free to lol
Feel free to LOL
  • Mr. Stevenson has ____________attraction for staples at a 45 degree angle ,  _________ staple affinity values.
trends for electron affinity
TRENDS for electron affinity
  • Group: Tends to increase as you move up the group.
  • Period: Tends to increase as you move left to right across a period.
on back of blank sheet of paper2
On back of blank sheet of paper
  • Electron affinity size:

Periodic Table

See hermcast for an added explanation

electron affinity p158
electron affinity (p158)
  • periodic trend (left to right) – generally increases
    • nonmetals want to gain e- to have 8 valance electrons
    • Since size decreases they have the ability to gain electrons and they want to gain electrons to get 8 in their outer energy level since that is the most stable.
  • group trend – generally decreases
    • higher energy levels makes it more difficult for the extra electrons to be held to the atom
      • Shielding effect
periodic trends in ionic size
Periodic Trends in Ionic Size
  • This is always a comparison between an ion and an atom of the same element.
slide50

Metals lose electrons increasing the nuclear charge, causing the ion to be __smaller_ than the atom.

slide51

These arrows represent electron and the numbers represent the energy levels.

The size of the atom decreases since you are losing an energy level.

slide52

Non metals gain electrons decreasing the nuclear charge, causing the ion to be __larger_ than the atom.

slide53

The size of an atom increase when you add electrons since you have the same

Number of protons but now more electrons. The same number of protons cannot

Hold the extra electrons very well which allows them to move around a bit more.

valence electrons
Valence Electrons
  • Valence electrons have the highest energy level and are the most important because they are used in bonding.
slide55

Isoelectronic means having the same electron arrangement. Becoming isoelectronic to a noble gas_ means having the most stable electron arrangement possible. Atoms become stable when they become isoelectronic to members of group # 18.

draw on the back of the sheet
Draw on the back of the sheet
  • Isoelectric diagram:
  • Draw Li, Li+, and He
  • Draw F, F-, and Ne

See hermcast for an added explanation

slide57

Group # # of valence electrons

  • 1 1
  • 2 2
  • 13 3
  • 14 4
  • 15 5
  • 16 6
  • 17 7
  • 18 8
electronegativity
Electronegativity
  • Electronegativity (elneg) is a measure of the ability of an element to attract shared electrons , which are the type most commonly found in covalent bonds.
slide59

Because this is a way of gaining access to more electrons, metals have a low measure and nonmetals have high measures.

trends for electronegativity
Trends for electronegativity
  • Group: Tends to increase as you move up the group.
  • Period: Tends to increase as you move left to right across a period.
on back of blank sheet of paper3
On back of blank sheet of paper
  • Electronegativity:

Periodic Table

See hermcast for an added explanation

density
DENSITY
  • Gases are _less___dense than liquids which are _less___dense than solids.
  • TRENDS:
  • Tends to increase as you move down a group and decrease as you move left to right across a period.
on back of blank sheet of paper4
On back of blank sheet of paper
  • density:

Periodic Table

See hermcast for an added explanation