Periodic Table -> an arrangement of the elements that shows that similarities between elements.

Transcription

1 Periodic Table -> an arrangement of the elements that shows that similarities between elements.

2 Periodic Table -> an arrangement of the elements that shows that similarities between elements. Group / Family = the columns within the periodic table.

3 Periodic Table -> an arrangement of the elements that shows that similarities between elements. Group / Family = the columns within the periodic table. Series / Periods = the horizontal rows within the periodic table.

4 Periodic Table -> an arrangement of the elements that shows that similarities between elements. Group / Family = the columns within the periodic table. Series / Periods = the horizontal rows within the periodic table. Periodic Law -> law stating that many of the physical and chemical properties of the elements tend to recur in a systematic manner with increasing atomic number.

5 But why do elements have similar properties?

6 But why do elements have similar properties? Let s look at the electron configuration for a couple of elements: Magnesium (Mg) 1s 2 2s 2 2p 6 3s 2 Calcium (Ca) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 What do you see that they have in common in respect to their electron configurations?

7 But why do elements have similar properties? Let s look at the electron configuration for a couple of elements: Magnesium (Mg) 1s 2 2s 2 2p 6 3s 2 Calcium (Ca) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 What do you see that they have in common in respect to their electron configurations? Both magnesium s and calcium s electron configurations end in s2. In fact each of the elements in that group end in s2 - it is this similarity that makes them have similar properties.

8 But why do elements have similar properties? Let s look at the electron configuration for a couple of elements: Magnesium (Mg) 1s 2 2s 2 2p 6 3s 2 Calcium (Ca) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 What do you see that they have in common in respect to their electron configurations? Both magnesium s and calcium s electron configurations end in s2. In fact each of the elements in that group end in s2 - it is this similarity that makes them have similar properties. So within a GROUP of the periodic table the elements have electron configurations that end in the same sublevel.

9 A little history, that you WILL need to remember: The first working periodic table was developed by a Russian chemist who was trying to come up with a presentable order of the elements for his students. Dimitri Mendeleev noticed that when the elements, known at that time, were listed in increasing order of atomic mass, that a regularly occurring pattern of properties developed.

10 A little history, that you WILL need to remember: The first working periodic table was developed by a Russian chemist who was trying to come up with a presentable order of the elements for his students. Dimitri Mendeleev noticed that when the elements, known at that time, were listed in increasing order of atomic mass, that a regularly occurring pattern of properties developed. In fact using this new found way of grouping the elements Mendeleev was able to predict the properties of several elements that had not been discovered at that time.

11 This is an example of what Mendeleev s Periodic Table might have resembled:

12 A little history, that you WILL need to remember: But there was a problem with this order. Let s look at it.

13 A little history, that you WILL need to remember: But there was a problem with this order. Let s look at it. 52 Te tellurium What do you notice about these two elements? 53 I iodine

14 A little history, that you WILL need to remember: But there was a problem with this order. Let s look at it. 52 Te tellurium What do you notice about these two elements? 53 I iodine You should notice that the atomic mass decreases from left to right

15 A little history, that you WILL need to remember: But there was a problem with this order. Let s look at it. 52 Te tellurium What do you notice about these two elements? 53 I iodine You should notice that the atomic mass decreases from left to right so according to Mendeleev they would be in the reverse order, or OUT OF PLACE.

16 A little history, that you WILL need to remember: So as you will notice now the elements in the periodic table are now in order of ATOMIC NUMBER.

17 A little history, that you WILL need to remember: So as you will notice now the elements in the periodic table are now in order of ATOMIC NUMBER. This is the work of Henry Moseley.

18 Now back to basics of the Periodic Table: METALS physical prop. - luster, malleable, ductile, conduct electricity, most are room temp. chemical prop. - while varied most will react with acids to release hydrogen gas

19 Now back to basics of the Periodic Table: NONMETALS physical prop. - dull, brittle, do not conduct electricity, most are gases or room temp.

20 Now back to basics of the Periodic Table: METALLOIDS these are elements that are thought to have properties of both metals AND nonmetals.

21 Now more basics: Group 1: Alkali Metals are the most reactive of the metals. (In fact they are never found free in nature.) are the least dense of the metals. (In fact they can be easily cut with a knife.) have a high luster. react readily with Group 17 elements to make salts.

22 Now more basics: Group 2: Alkaline Earth Metals are reactive but not as reactive as Grp 1. are more dense than Grp 1 metals. have a high luster. react with water to form alkaline (basic) solutions. (ph > 7)

23 Now more basics: Groups 3-12: Transition Elements are not reactive as the Representative Elements. have a varying number of electrons in their outermost energy level.

24 Now more basics: Lanthanide & Actinide Series all fill the f sub level, elements w/ atomic numbers > 92 are artificially made.

25 Now more basics: Group 17: Halogens from the Greek for salt makers. are the most reactive of the nonmetals. always found in the combined state, whether combined with another elements or themselves as diatomic molecules.

26 Now more basics: Group 18: Noble Gases once known as the inert gases. are the least reactive of all the elements.

27 Review On the piece of paper provided answer each of the following questions. 1. Why are the properties of each element unique? 2. Which of the following would have properties similar to copper: silver or manganese? Explain. 3. Identify each as a metal, nonmetal, metalloid or noble gas: (a) barium, (b) boron, (c) krypton (d) lead 4. State periodic law. 5. Assume a new element has been discovered. It has a high luster and only conducts electricity moderately. To which area of the periodic table does it belong and why?