Notes One Unit Three Chapter Four

• Early Periodic Tables• Modern Periodic Table• Orbitals on The Periodic Table• Elements of Life• Dot Diagrams

Lab B: PROCEDURE A: ALKALINE EARTH METALS AND WATER 1. Obtain a 2-3 cm piece of magnesium and a piece of calcium metal using tweezers. Examine

their appearances. Hold each metal with the tweezers and scrape off the surface until you see a shiny surface. Record your observations:

a) What clues does the surface appearance of these metals give you about the reactivity of these two metals with air?

• 2. Fill two test tubes half-full with tap water. Tap water is not pure H2O, but is not going to alter these pH tests. Put the tubes in your test-tube rack. Test the pH (acidic or basic property of the solution) by dipping a stirring rod into the water and touching it to a piece of Universal Indicator paper. Record observations.

• 3. Drop a small piece of calcium metal into one of the test tubes and a small piece of magnesium into the other. Observe and record. (Caution the reaction can be very hot.)

• b) From what you observe in the test tubes, what can you state about the reactivity of these two metals with water?

• c) You have seen a demonstration of the reactivity of the alkali(Li vs Na) metals with water. What do you predict about the reactivity of strontium metal with water and air as compared to magnesium and calcium?

Lab B: PROCEDURE A: ALKALINE EARTH METALS AND WATER

• 4. Test the pH of the solutions in the test tubes again. Record your observations.

• 5. The white substance formed in the reaction is an ionic compound. Make a hypothesis about what this product is. Then do a pH experiment with the available salt(s) of your choice and see whether the pH result is consistent with the pH measured in Step #4. (Four salt samples of Ca(OH)2, CaCl2, MgCl2 and CaO are available at the end of the lab bench for you to use. Take very small amounts of these and add a small amount of water to each in a Petri dish as below on the right in figure 1.

• Hypothesis:

• d) In one of the reactions above you should have seen bubbles of gas being formed. Of what do you suppose these bubbles of gas are made?

Lab B: PROCEDURE A: ALKALINE EARTH METALS AND WATER

• Summary Questions: • l. What general properties can you state regarding alkaline earth metals (both

chemical and physical) after this exploration?

• m. Your mother has probably told you that calcium is an important part of your diet. Do you think it would be reasonable for you to eat calcium metal atoms as a dietary calcium supplement? Explain.

• n. Do you think your bones and teeth contain calcium metal atoms or calcium ions?

• o. Strontium-90 is a radioactive isotope of strontium that is a dangerous product of nuclear fallout whether from nuclear weapons’ blasts or from nuclear reactor accidents. Based upon your understanding of similarities of properties of elements in a chemical family, explain why this isotope of strontium ions is so dangerous to humans if it is spread around in the environment. (Hint: where do you think the Sr would go in your body?)

Electron Shielding Explanation

12 e-1

How many e-1 for Mg ?

20 e-1

How many e-1 for Ca?

+12 +20

How many protons? How many protons ?

What is the Short-Hand element in each case?Ne Ar

Do the nuclear protons attract or repel the e-1?Do the short-hand e-1 attract or repel the e-1?

Early Periodic Tables• John Newland’s

law(1837-1898)• Organized by • (a)Octaves • (b) Mass

• Demetri Mendeleev (1834-1907)

• Proposed arranging elements by

• (a) Properties• (b) Mass

Dobereiner and Triads

• From the Dobereiner’s law of triads, the atomic mass of the middle element, in this case Na, should be the arithmetic mean of Li and K.

• arithmetic mean of Li and K (7 + 39)/2 = 23

Elements   Symbol mass

Lithium Li 7

Sodium Na 23

Potassium K 39

Modern Periodic Table • Organized Rows (period)• Columns (Families):• Alkali Metals• Alkaline Earth Metals• Transition Metals• Rare Earth Metals• Other Metals• Metalloids • Non-Metals• Halogens• Noble Gases• Atomic Number (Henry Moseley 1913

X-rays)• Two Main groups: • Metals • Nonmetals

Modern Periodic Table

Modern Periodic Table

Modern Periodic Table

Orbitals on The Periodic Table

f-block

d-blockp-block

s-block

Electron Configurations• Most stable elements are He, Ne, Ar, Kr, Xe and Rn.• Most Unstable Metals are H, Li, Na, K, Rb, Cs, Fr• Most Unstable Nonmetals are F, Cl, Br, I, and At

Alkali Metals

Alkaline Earth Metals

Halogens

Noble Gases

Elements of Life

Dot Diagrams

Notes Two unit Three Chapter Four

• Halogens Lab Observation• Halogens Lab Explanation• Valence Versus Kernel Electrons• Electron Shielding• Increasing Atomic Number• Highest Energy Level Occupied• Atomic Radii• Ionization Energy• Other Trends

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

+17

←

←

← ← ←

← ←

Ne1s2s

2p3s

3p4s

3d4p

←

←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←

←

←

← ← ←← ← ←

←

←

←

←← ← ←

← ←

+35

Br

Ar 1s2s

2p3s

3p4s

3d4p

5s4d

5p←

←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←

←

←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←

←

←

←

←

← ← ←

← ←

+53

I

Kr

Do a complete workup on each element.Bromine’s shielding(Ar) is great than Chlorine’s shielding(Ne)

Bromine’s valence e-1’s are further from the nucleus than Chlorine’s valence e-1’s.

Iodine’s valence e-1’s are even further from the nucleus and have yet greater shielding.

Electronegativity

3.160

Cl

2.960

2.660

Halogen comparative Reactivity

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

←

+11

Na

1s2s

2p3s

3p4s

3d4p

←

←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←

←←

←←

← ← ←

← ←

+35

Br

NaBr(aq)Colorless SolutionSodium lost an e-1 to bromine.Sodium is stable like which noble gas?neonBromide is stable like which noble gas?krypton

Halogens Lab:NaBr

If chlorine comes along, what will happen?

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

+17

←

←

← ← ←

← ←

ClYellow-green

←

←

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

←

+11

Na

1s2s

2p3s

3p4s

3d4p

←

←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←

←←

←←

← ← ←

← ←

+35

Br

When chlorine takes the e-1 from bromide, what do we see?Chlorine(Yellow-green) turns in to chloride(colorless)

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

+17

←

←

← ← ←

← ←

ClYellow-green

←

←

Bromide(colorless) turns in to bromine(orange)

Halogens Lab:NaBr

NaI(aq)Colorless Solution

Halogens Lab:NaI

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

+11

Na

1s2s

2p3s

3p4s

3d4p

5s4d

5p

←

←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←←

←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←←

←

←

←

← ← ←

← ←

+53

I

Sodium lost an e-1 to iodine.Sodium is stable like which noble gas?neonIodide is stable like which noble gas?xenonIf brome comes along, what will happen?

1s2s

2p3s

3p4s

3d4p

←

←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←

←

←

←

←

← ← ←

← ←

+35

Br

←←

←

1s2s ←

←←

+3Li

1s2s

2p3s

←←

←←

← ← ←

← ← ←

←

+11

Na

1s2s

2p3s

3p←

←←

←

← ← ←

← ← ←

←

+19

K

4s←

←

← ← ←

← ← ←

1s2s

2p3s

←

←

←

←

← ← ←

← ← ←

←

+12

Mg

←

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

←

+20

Ca

4s

←

←

← ← ←

← ← ←

←

Metallic Reactivity Versus Shielding

He

Ne Ne

Ar Ar

Do a complete workup on each element.Which is more reactive…Li, Na or K?Why is it more reactive?

Which is more reactive…Na or Mg?Why is it more reactive?

(1) more shielding e-1’s(2) valence electrons are further from the + charge of the nucleus.

(1) less protons to hold valence e-1’s. The e-1’s are lost more easily.

Electronegativity

0.980

0.930

0.820

1.310

1.000

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

←

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

←

←1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

←

←

←

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

←

←

← ←

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

←

←

← ← ←

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

←

←

← ← ←

←

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ←

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

←

←

← ← ←

← ← ←

+11 +12 +13 +14

+15 +16 +17 +18

Na?What is OFD for

Na

Mg? Al? Si? S? Cl? Ar?Which are the Kernel e-1’s for

Mg Al Si

P?

P S Cl Ar

Na? Mg? Al? Si? S? Cl? Ar?P?

Ne Ne Ne Ne

Ne Ne Ne Ne

Properties change due to increasing atomic # horizontally0.930 1.310 1.610 1.900

2.190 2.580 3.160

Atomic Radii Left to Right on the periodic table• What does the # of kernel e-1’s say about shielding’s action on atomic radii from left

to right on the periodic table?• How does Highest Energy Level Occupied action on atomic radii from left

to right on the periodic table?• Highest Energy Level Occupied does not affect size from left to right.• What does this say about Increasing atomic # action on atomic radii from left to

right on the periodic table?

All are the 2nd NRG in this case

Increasing atomic # shrinks size.

Shielding has no effect on size left to right

1s2s ←

←

←

+3Li

1s2s

2p3s

←

←

←

←

← ← ←

← ← ←

←

+11

Na

1s2s

2p3s

3p

←

←

←

←

← ← ←

← ← ←

←

+19

K

4s

←

←

← ← ←

← ← ←

He

Ne

Ar

Atomic Radii Top to Bottom on the periodic table• What does # of kernel e-1’s say about shielding?

• How does Highest Energy Level Occupied action on size

• What does this say about Increasing atomic # action on atomic radii from Top to Bottom

Shielding increases size Top to Bottom

Highest NRG Level increases size Top to Bottom

Increasing atomic # has no effect on size

Ionization Energy

• The ionization energy or ionization potential is the energy necessary to remove an electron from the neutral atom.

• How does ionization energy compare to atomic radii?

Other Trends

End