Unit 7:Periodic Table Notes. Essential Question: Describe the differences between nonmetals, metalloids and metals.

Transcription

1 Unit 7:Periodic Table Notes Essential Question: Describe the differences between nonmetals, metalloids and metals. 1

2 Red stair step line separates metals from nonmetals Groups/families vertical Have similar physical and chemical properties Periods horizontal Periods do not have similar properties Periodic Table Organization 2

3 Metals Conduct heat Conduct electricity Ductile Malleable Can be hard or soft 3 or less valence electrons Left side of red line Sodium 3

4 Metalloids Has properties of both metals and non metals Touch the red line Boron 4

5 Nonmetals Does not conduct heat well Does not conduct electricity well Solids are brittle Most are gases at room temperature 5 or more valence electrons Right side of red line Nitrogen 5

6 The alkali metals. These elements are metals. Group 1 or IA 1 valence electron soft metallic solids Good conductors of heat and electricity very reactive with water to produce hydrogen gas and lots of heat(exotherimic) ionize by losing their electron, so the ion has a +1 charge Hydrogen is not considered an alkali metal. However, under the right conditions, hydrogen can behave like an alkali metal. Periodic Table Organization 6

7 The alkaline earth metals These elements are metals. Group 2 or IIA 2 valence electrons metallic solids, harder than the alkali metals Good conductors of heat and electricity exothermic reaction with water. ionize by losing their valence electrons, so the ion has a +2 charge Periodic Table Organization 7

8 The largest family of elements consist of transition metals. Groups 3-12 or IB to VIIB valence electrons vary hard metallic solids Good conductors of heat and electricity dense high melting points Periodic Table Organization 8

9 The boron group. Group 13 or IIIA 3 valence electrons diverse properties, intermediate between those of metals and nonmetals best known is aluminum Periodic Table Organization 9

10 The carbon group. Group 14 or IVA 4 valence electrons diverse properties, intermediate between those of metals and nonmetals best known is carbon, which commonly forms 4 bonds Periodic Table Organization 10

11 The nitrogen group Group 15 or VA Nitrogen Group 5 valence electrons diverse properties, intermediate between those of metals and nonmetals ionize by gaining 3electron, so the ion has a -3 charge Periodic Table Organization 11

12 The oxygen group. Group 16 or VIA 6 valence electrons diverse properties, changing from nonmetallic to metallic as you move down the family ionize by gaining 2 electrons, so the ion has a -2 charge Periodic Table Organization 12

13 The halogen family These are nonmetals Group 17 or VIIA 7 valence electrons Very reactive nonmetals high electron affinities- attraction to electrons ionize by gaining an electron, so the ion has a -1 charge Periodic Table Organization 13

14 The noble gases These are nonmetals. Group 18 or VIIIA 8 valence electrons Do not form compounds stable electron octet makes these elements unreactive under ordinary circumstances Periodic Table Organization 14

15 Unit 7:Periodic Trends Essential Question: How does atomic size and ionization energy change across a period and down a group? 15

16 What influences periodic trends? Influenced by three factors: 1. Energy Level Higher energy levels are further away from the nucleus. 2. Charge on nucleus (# protons) More charge pulls electrons in closer. (+ and attract each other) 3. Shielding effect- Outer electrons shielded from influence of nucleus 16

17 How is Atomic Size determined? Atomic radius one half the distance between the nuclei of two atoms of the same element 17

18 How does atomic size change going across PT? Leaving the noble gases out, atoms get smaller as you go across a period. Electrons are in the same energy level. But, there is more nuclear charge. The electrons are pulled closer. 18

19 How does atomic size change down a group? As we go down a group, each atom has another energy level, so the atoms get bigger. 19

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21 What is Ionization Energy? Energy required to remove an electron How does IE change across the PT? IE increase from left to right across PT The greater the nuclear charge, the greater IE, because All the atoms in the same period have the same energy level. Same shielding. But, increasing nuclear charge 21

22 Why does IE decreases down a group? Greater distance from nucleus decreases IE. The electron is further away from the attraction of the nucleus, and There is more shielding. 22

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24 Essential Question: Describe how electronegativity changes down a group and across a period. 24

25 What is Electronegativity(EN)? the ability of an atom to attract electrons when the atoms is in a compound Metals have low EN Non-metals have high EN 25

26 How does electronegativity change across a period? Electronegativity increases from left to right across a period(noble gases have no EN) Because the greater nuclear charge attracts electrons. 26

27 How does electronegativity change down a group? EN decreases as you go down a group. because the farther away an electrons is from the nucleus, the more likely an atom is to lose an e- than gain an e-. Shielding makes it more difficult to attract e-. 27