IONIZATION ENERGY

Ionization energy: The energy required to remove an electron from an gaseous atom or an ion. Measure in Joules. Think of it as a measure of how strongly an atom holds onto its electrons. The more energy required to remove it, the greater hold the nucleus had on it.

Trend: Ionization energy increases across a period This is due to increase of nuclear charge and decreasing radii. (it is harder to remove an electron) Ionization energy decreases down a group This is due to increasing radii and decreasing nuclear charge. ( it is easier to remove an electron.

Ionization Energy Trend Kent. "KentChemistry Movie Page." Mr. Kent's Chemistry Regents Help and AP Chemistry Exam Review Pages. Web. 25 Oct

Review Questions 1. What is ionization energy? 1. The energy required to remove one electron from neutral atom of an element. 2. The energy that occurs when an atom is added to a negative ion. 3. An ion’s energy that is required to move a neutral atom out of the nucleus 4. The energy required to add one electron to the neutral atom of an element. 1.

Review Questions 2. What trend does ionization energy have? 1. Decrease across a period and decreases down a group. 2. Increase across the period and decrease down a group. 3. Increase across a period and increases down a group. 4. Decrease across the period and increases down a group. 2.

Review Questions What group has the lowest Ionization Energy? a) D- block b) Group 17 Halogens c) Group 18 Noble Gas d) Group 1 Metals d

Review Questions What is responsible for increasing Ionization Energy? a) Increasing Nuclear Charge b) Decreasing Nuclear Charge c) Increase Electron Affinity d) Increase Ionic Radii a.

Review Questions What is the label for Ionization Energy? a) Ions b) Mole c) kJ or J d) kJ/mol c.

Electron Affinity

Electron Affinity: “The energy change that occurs when an electron is acquired by an neutral atom.” (Modern Chemistry, p 157) The energy change is negative (which means that energy is released). The more energy that is released, the more negative the number. Definition:

 Trend across: 1. Increases 2. Why? The elements want to gain more electrons because the elements want to get a full orbital. Trends of Electron Affinity:  Trend down: 1.Either decreases or stays the same 2.Why? A slight increases the nuclear charge and increase in atomic radius.

Period Trend The electron affinity increases as you go across the periods because elements want to gain electrons to reach stable configuration as you go to the right.

Group Trend The electron affinity decreases as you go down in the columns because it gets more difficult to add electrons to an atom that already has many that are further from the nucleus.

Pictures:

1. What is electron affinity? Review Questions: The energy change that occurs when an electron is acquired by an neutral atom. Increases 2. What is the trend across for electron affinity?

3. What is the trend down? Either decreases or stays the same Bromine (-336.5) 4. Which element is higher: Potassium or Bromine

5. Which element is lower: Oxygen or Polonium? Oxygen(-146.1) The quantity of energy absorbed would be represented by a positive number, but the energy released would be represented by a negative number. If more energy releases a higher number occurs. The negative is just the lose of energy. 6. Why are the numbers negative?

Electronegativity

“A measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound” (Modern Chemistry). The better they are at attracting electrons, the higher the number. Subtracting the electronegativities of two elements, indicates the type of bond that they would form.

trend Electronegativites generally increase from left to right across the period. The energy levels want 8 electrons. Energy levels fill up making them more capable of attracting electrons from another atom.

trend Electronegativites will generally decrease down a group or stay about the same. Because of the ending sublevel of p 6.

why? Every element wants to fill its entire energy level up to p 6. As atoms get closer to having eight electrons in an energy level, they attract electrons more strongly. (s 2, p 6 )

Range of electronegativity Lowest:0.7 (Francium) Highest: 4 (Fluorine) Range:

Range of electronegativity Unit: no unit it is more like a ranking. Subtracting electrongativities will predict the type of bond Covalent (difference of 0-0.3) Share electrons Polar covalent (difference of ) Share electrons unevenly Ionic (difference of greater than 1.7) Transfer electrons

Review Questions 1. What is the most electronegative element on the periodic table? 2. What is the range of electronegativity? 3. As you go across a period, do the levels of electronegativity increase? Or decrease? Fluorine Increase

Review questions 4. What is the least electronegative element in the periodic table? 5. What is the sublevel every atom wants to be at? 6 What scale is electronegativity measured by? Francium p6p6 Pauling scale (a scale that ranks)

Atomic Radius

Definition “Half the distance between identical atoms that are bonded together.” (Modern Chemistry) Half the distance between metal ions that are next to each other. Measured distance of pm (picometers)

Trend Going down Atomic Radius increases down a family. The number of valence electrons remains the same The trend in larger atoms going down a group is due to adding electrons to subsequent energy levels.

Trend Going Across The atomic radius decreases across a period. “The trend to smaller atoms across the period is caused by the increasing positive charge of the nucleus.” (Modern Chemistry)

Why does it Occur “The trend to smaller atoms across the period is caused by the increasing positive charge of the nucleus.” (Modern Chemistry)

Unit Atomic Radius is measured in picometers (pm) (Modern Chemistry)

Smallest Elements Neon with 38pm, and Hydrogen with 25pm them two are the smallest in atomic radius. And is always positive and never negative.

Largest Elements Cesium has the largest atomic radius going from 273.1pm to 260pm and Rubidium comes next with an atomic radius around 30. But is still always positive.

Question 1 What is the largest atomic radius going from pm to 260pm. Answer: Cesium

Question 2 The number of valence electrons stays the same in atomic radius. T or F Answer: T

Question 3 Atomic Radius is used in pictometers? T or F Answer: T

Question 4 As the trend goes across the electrons? A. Increase B. Decreases C. Stays the same Answer: A

Question 5 What are the smallest element in atomic radius? A. Lithium and neon B. Hydrogen and copper C. Hydrogen and Neon D. None of the above Answer: C

Question 6 What are the largest elements in atomic radius? A-Radon and Lithium B-Cesium and Rubidium C-Francium and Uranium D-none of the Above Answer: B

Ionic Radius When atoms lose electrons and become cations, the atoms become smaller. They lose valence electrons The nucleus pulls the rest in tighter. When atoms gain electrons and become anions, they atoms become larger. They gain valence electrons The nucleus can’t pull them in as tightly.

Trends Across a period- On the left the cations are smaller. On the right the anions are larger, but overall…Atomic radius decreases. Down a group-Atomic radius increases

Review True or False. The cations from group 1 to group 2 decreases. True

Review True or False. The anions on the right side of the periodic table decreases across the period. True