The Periodic Law (Periodic Table) CHAPTER FIVE

Brief History Original periodic table was constructed by Dmitri Mendeleev. This periodic table consisted of about 60 elements and was arranged in order of increasing atomic mass

Modern Periodic Table Our periodic table is based on the work of Henry Mosely, who arranged the elements in order of increasing atomic number

Periodic Law Mosely’s and Mendeleev’s periodic table follows periodic law: This means that if elements are arranged in increasing atomic #, they will fall into groups that have similar properties.

Modern Periodic Table 18 vertical group/families 7 horizontal periods Divided into two main parts, metals and nonmentals.

Group 1 Elements Alkali Metals Most reactive of the metals Mostly Soft Solids

Group 2 Elements Alkaline Earth Metals Still very reactive More dense than the group 1 metals

Groups three through twelve Transitional Metals Elements “transition” from Metals to non-metals as you move across the table metallic properties

Group 17 Halogens Non-metals most reactive of nonmetals.

Group 18 Noble gases Nonmetals Least reactive of non-metals

Left Side of the periodic table Metals Shiny Malleable Ductile Conducts electricity Conducts Heat Mostly solids

Inbetween are the “Others” Other Metals (Have metallic properties) Al, Ga, In, Sn, Bi, Pb, Tl Metalloids-Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, Polonium Properties of both metals and non-mentals Semiconductors-used in electronics Other Non-Metals (Have non-metal properties) C, N, O, P, S, Se, H

Right side of periodic table Non-Metals Do not conduct electricity or heat well Some brittle solids Some gasses

Check for understanding Which group/family is each element in? Al Ar K Pd Br Ca Zn Si Based on the group/family each element below are in, name 2 properties of : 9. K 10. P 11. Cl 12. Ga

Periodic Trends Elements have characteristics that tend to increase or decrease as one moves along a row or column of the periodic table of elements.

Atomic Radii Atomic Radii-The distance from the center of the nucleus to the edge of the atom’s electron cloud. Atomic Radii

Atomic Radii Trending Activity Grapher Straw Cutter Recorder We will use our current knowledge of the atom to try and predict the trend for atomic radii. We will then test our hypothesis by actually graphing real data and then making a 3-D model of the trend.

Atomic Radii Continued Trend in each period Why do you think the radius decreases to the right if there are more protons to the right? Shouldn’t that make the radius increase? As there are more protons they pull more strongly on the electrons that are surrounding them. Each period is within the same energy level.

Atomic Radii Continued Trend in each group Why do you think the radius increases as you go down a group if more protons means they pull harder on the electrons? As you go down a group you are adding energy levels which makes the radius increase.

Atomic Radii Continued Periodic Table Trend: Increases to the left Increases going down Increasing Size

Atomic Radii Practice K or Ni Ne or Xe Rb or In 4. Al, K, Ne, H In each pair which of the following has the largest Atomic Radii? K or Ni Ne or Xe Rb or In Arrange the following in order of increasing atomic radii? 4. Al, K, Ne, H 5. Will a larger atomic radii make an atom more or less likely to give away an electron?

Quiz Place the following in order using decreasing Atomic Radii : Au, Ba, O, Cl & Pb Cl or I Which of the above pair has the largest atomic radii? Why does the table trend that way? Who created the 1st periodic table? What was the 1st periodic table arranged by? The vertical columns are called what? Elements within the same column will have _________ properties. What is the name of each of the following groups? 18 2 1 Which group name does Ge fall under? Name 4 popertiesA

Ionization Energy (IE) 1st Ionization Energy-Energy required to remove one electron from an un-bonded atom. (individual atoms) Basically: How hard is it to get an electron away from an atom? No, Mine! Mine! e-

Ions ION-an atom that has a positive or negative charge.

Ionization Energy (IE) A lost electron will create a Positive Ion Positive Ion is a Cation + + + + + + + Pawsitive : )

Ionization Energy (IE) A gained electron will create a negative ion Negative ions are called Anions

Ionization Energy (IE) Continued Trend across a period? Decreases to the left Trend in a group/family? Decreases going down Which Group would have the lowest first Ionization energy? (who is it easiest to take an electron from?) Group 1 Why? They want to get rid of that 1 valence electron Which group would have the highest first ionization energy? Group 18 They do not want to lose one of their 8 valence electrons ( they are happy the way they are)

Ionization Energy Periodic Table Trend: Decreases to the left Decreases going down Decreasing Decreasing

Ionization energy practice Which element within the following pairs has the highest ionization energy? K or Be B or Ga O or Ca Ar or Sb Arrange the following in decreasing Ionization energy (meaning from Highest to lowest) Li, O, C, K, Ne, F

Electronegativity Electronegativity-Measurement of how strongly one atom attracts the electrons of another atom in a compound. Developed by Linus Pauling Which element do you think would be the most electronegative? Fluorine-4.0. All other values are calculated in relation to Fluorine’s value. Scientest just picked the number 4. It wasn’t really based on anything.

Electronegativity & (FON) Oxygen, Nitrogen and then the other halogens are the most Electronegative after fluorine. F, O, N – Top 3 highest electronegativity

Electronegativity Periodic Table Trend: Decreases to the left Decreases going down Decreasing Decreasing

Electronegativity Practice Which of each pair has the greatest EN? a. Ca or Ga b. Br or As c. Li or O d. Ba or Sr e. Cl or S f. O or S Rank the following elements by increasing EN: sulfur, oxygen, neon, aluminum. Answer: Ne,Al,S,O

Definition in your own words Trending Challenge  Terms Definition in your own words Single atoms or bonded atoms? Element with smallest Element with largest Atomic Radii Ionization Energy Electro-negativity

Review 1. The elements characterized as nonmetals are located in the periodic table at the (A) left; (B) bottom; (C) center; (D) top right 2. Which is the atomic number of an alkali metal? (A) 10; (B) 11; (C) 12; (D) 13. 3. Which element is a halogen? (A) iron; (B) nitrogen; (C) iodine; (D) neon 4. Which Group 17 element has the least tendency to gain electrons? (A) fluorine; (B) iodine; (C) bromine; (D) chlorine. 5. The alkaline earth element having the largest atomic radius is found in Period (A) 1; (B) 2; (C) 6; (D) 7. 6. Which of the following atoms will lose an electron the easiest? (A) potassium; (B) calcium; (C) rubidium; (D) strontium

Electron Affinity Electron Affinity-The energy change that occurs when an individual atom gains an electron. The more an atom “loves” getting another electron the more the energy it will release. . . _ . . + Electron Atom

Electron Affinity Which group is “happiest” to take on an electron? Group 17 Why? They are 1 electron away from a full outer shell (Valance Shell)

Electron Affinity Group 1 and Group 18? Why? Which groups care nothing for additional electrons? Group 1 and Group 18? Why? Group 18 is totally happy with their 8 electrons Group 1 is closer to being happy by giving away it’s 1 valance electron.

Electron Affinity Periodic Table Trend: Decreases to the left Decreases going down Decreasing Decreasing

Electron Affinity Arrange by increasing Electron Affinity Which of the following has the greatest electron affinity? Al or Br O or C Xe or F Arrange by increasing Electron Affinity Cl, K, Fr, I Answer:Fr, K, I, Cl