03.03 Periodic Trends Assignment Details On

PART III: Analysis and Conclusion 1. Refer to the graph that you created in Part I of this assignment. Describe the general trend or pa±erns that you observed in the atomic radius as you go across the periodic table. The atomic radius decreases as it goes across the period table and the period number increase as it goes down groups.The atomic rasdius is bigger when the atomic number is smaller. 2.In Part II of this assignment, you graphed the atomic radius of some elements from group 14 on the periodic table. What is the general trend for atomic radius going down that group? It goes up with a slant. 3.What element in Period 5 of the periodic table is a member of Group 14? Tin(sn) 4.The word interpolate means to use a given line graph to Fnd unknown points between the plo±ed points of the graph. Use your line graph from Part II to interpolate, or es²mate, atomic radius of Tin (Sn).

Presentation on theme: "Trends in the Periodic Table"— Presentation transcript:

1 Trends in the Periodic Table

2 Atomic RadiusAtomic radius is simply the radius of the atom, an indication of the atom's volume.Atomic radius is one-half the distance between the two nuclei in a molecule consisting of two identical atoms.

3 Trends in Atomic Size cont.
Group - atomic radius increases as you go down a group.Why?There is a significant jump in the size of the nucleus (protons + neutrons) each time you move from period to period down a group.Additionally, new energy levels of electrons clouds are added to the atom as you move from period to period down a group, making the atom significantly more massive, both in mass and volume.

4 Trends in Atomic Size- Period - atomic radius decreases as you go from left to right across a period.Why? Stronger attractive forces in atoms (as you go from left to right) between the opposite charges in the nucleus and electron cloud cause the atom to be 'sucked' together a little tighter.

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6 Ionization EnergyIonization energy is the amount of energy required to remove the outermost electron/s.Ionization energy is closely related to electronegativity.

7 Ionization Energy Trends cont.
Group - ionization energy decreases as you go down a group.Why? The shielding affect makes it easier to remove the outer most electrons from those atoms that have many electrons (those near the bottom of the chart).

8 Ionization Energy Trends
Period - ionization energy increases as you go from left to right across a period.Why? Elements on the right of the chart want to take others atom's electron (not given them up) because they are close to achieving the octet. The means it will require more energy to remove the outer most electron. Elements on the left of the chart would prefer to give up their electrons so it is easy to remove them, requiring less energy (low ionization energy).

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10 ElectronegativityElectronegativity is an atom's 'desire' to grab another atom's electrons.

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12 Electronegativity Trends cont.
Group - electronegativity decreases as you go down a group.Why? Elements near the top of the period table have few electrons to begin with; every electron is a big deal. They have a stronger desire to acquire more electrons. Elements near the bottom of the chart have so many electrons that loosing or acquiring an electron is not as big a deal. This is due to the shielding affect where electrons in lower energy levels shield the positive charge of the nucleus from outer electrons resulting in those outer electrons not being as tightly bound to the atom.

13 Electronegativity Trends
Period - electronegativity increases as you go from left to right across a period.Why? Elements on the left of the period table have 1 -2 valence electrons and would rather give those few valence electrons away (to achieve the octet in a lower energy level) than grab another atom's electrons. As a result, they have low electronegativity. Elements on the right side of the period table only need a few electrons to complete the octet, so they have strong desire to grab another atom's electrons.

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15 Reactivity vigorously an atom is to react with other substances.
Reactivity refers to how likely orvigorously an atom is to react with other substances.This is usually determined by two things:

16 1) How easily electrons can be removed (ionization energy) from an atom

17 2) or how badly an atom wants to take other atom's electrons (electronegativity)

18 The transfer/interaction of electrons is the basis of chemical reactions.

19 Reactivity of MetalsPeriod - reactivity decreases as you go from left to right across a period.Group - reactivity increases as you go down a groupWhy? The farther to the left and down the periodic chart you go, the easier it is for electrons to be given or taken away, resulting in higher reactivity.

20 Reactivity of Non-Metals
Period - reactivity increases as you go from the left to the right across a period. Group - reactivity decreases as you go down the group.Why? The farther right and up you go on the periodic table, the higher the electronegativity, resulting in a more vigorous exchange of electron.

21 Ionic Radius vs. Atomic Radius
Metals - the atomic radius of a metal is generally larger than the ionic radius of the same element.Why? Generally, metals loose electrons to achieve the octet. This creates a larger positive charge in the nucleus than the negative charge in the electron cloud, causing the electron cloud to be drawn a little closer to the nucleus as an ion.

22 Ionic Radius vs. Atomic Radius cont.
Non-metals - the atomic radius of a non-metal is generally smaller than the ionic radius of the same element.Why? Generally, non-metals gain electrons to achieve the octet. This creates a larger negative charge in the electron cloud than positive charge in the nucleus, causing the electron cloud to 'puff out' a little bit as an ion. 

23 Ionic Radius vs. Atomic Radius

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