Presentation is loading. Please wait.

Presentation is loading. Please wait.

Periodic Law The nucleus of the atom exerts forces upon its electrons that make them have distinctive traits or trends. What are these trends and how are.

Similar presentations


Presentation on theme: "Periodic Law The nucleus of the atom exerts forces upon its electrons that make them have distinctive traits or trends. What are these trends and how are."— Presentation transcript:

1 Periodic Law The nucleus of the atom exerts forces upon its electrons that make them have distinctive traits or trends. What are these trends and how are they inter-related?

2 The atom - review What are the three “players” in the inner workings of an atom? Protonpositively charged(+1) Neutronneutrally charged(+0) Electronnegatively charged(-1) elementary charge = × coulombs

3 The atom - review What is the geometry that atom takes? Nucleus : protons and neutrons Electron Orbital or shell

4 Mendeleev’s Table Meyer’s table grouped elements by the atom’s valence electrons (outer electrons) Mendeleev said that not only is valence important but he also grouped elements by atomic mass and known chemical properties His claim to fame was that he predicted missing elements and “foretold” their properties.

5

6 Period Table Metals Non-metals Metalloids

7 Properties of Matter Metals Most are solid at room temperature Good conductor of heat and electric current Lustrous (shiny) Malleable (easily flattened) Ductile (easily stretched – as into a wire) Non-metals Most are gases at room temperature Poor conductors of heat and electricity Dull (as in not reflecting light well) Brittle Metalloids: have properties common to both Metals and Non-metals

8 Period Table – Family Names Nobel Gases Alkali Metals Alkaline Earth Metals Halogens Transition Metals Alkali Metals Lanthanide Series Actinide Series Pnictides Chalcogens

9 Period Table - Blocks s-block f-block d-block p-block

10 Modern Chart Instead of arranging elements on the chart by atomic mass (with special exceptions) the modern chart arranges elements primarily by atomic number (# of protons an element has) Which leads us to our first Periodic Trend

11 How we describe trends We express trends as we move along the periodic table 1.Top to Bottom 2.Left to Right

12 1 st Trend – Nuclear Charge “The Master Trend” The nucleus holds the atom’s protons and neutrons The number of proton an atom has defines that element and it also influences all the other trends we will examine

13 1 st Trend – Nuclear Charge “The Master Trend” Does the Nuclear Charge increase or decrease as we move from the top of the chart down? Increases (follow the atomic number) Does the Nuclear Charge increase or decrease as we move from left to right? Increases (follow the atomic number)

14 Electron Configuration Before we can examine more periodic trends we have to consider the electron The electron is actually the “employee” to the nucleus’s “management role” Except for nuclear chemistry, the interaction of the electrons between elements is where all of chemistry takes place

15 Electron Configuration Electrons reside in shells (or orbitals) Each “block” contains a different number of shells 4 types of blocks – s, p, d, f (some people dress funny)

16 Electron Configuration Each block has so many orbitals (s=1, p=3, d=5, f=7) Each orbital can hold up to 2 electrons Block# of OrbitalsMax Number of e - s (ome)1 (odd #s)2 (Orb. X 2) p (eople)36 d (ress)510 f (unny)714

17 Electron Configuration How we label the Electron’s locations follows this pattern: Row # Shell Letter Electron #2s 2

18 Atomic Radius Defined – the size of the atom (exactly the same as the radius of a circle) Even though we will be using 2-D pictures to demonstrate trends – they are really in 3-D and they have really “odd” shapes

19 Atomic Radius – Top to Bottom 3-D pictures of orbitals s/index.html s/index.html As we go from Top to Bottom the Atomic Radius increases

20 Atomic Radius – Left to Right Remember: as we go left to right on the periodic chart the number of protons (or nuclear charge) is increasing Remember that nuclear charge is a positive charge and electrons have a negative charge The effect on the radius of an atom is demonstrated in the following animation

21 Atomic Radius As we go left to right on the periodic chart, the effect of increasing nuclear charge decreases the radius of an atom

22 Ionization Energy Defined: the amount of energy needed eject an electron – thus making the atom an ion (or charged atom) As we move down the chart it gets easier to eject an electron because electrons are farther away from the nucleus and therefore held in the atom less securely As we move right it gets harder to eject an electron because electrons are closer to the nucleus and therefore held on more securely

23 New Way of Writing Electron Configuration Lets do Neon which has 18 electrons 2s1s 2p ↓↑↑↑↑↑↓↓↓ 3s ↓↑ 3p ↑↓↑↑↓↓↓

24 Electronegativity Defined – ability of an atom to attract (or steal) an electron from another atom or compound Nature “wants” to have a: Full shell first Empty shell next Half Empty third

25 Electronegativity With regards to Electronegativity “s” shells and “p” shells are considered one shell – we call these electrons valence electrons (meaning on the outside) as apposed to core electrons which are previously filled shells or energy levels Lets look at Fluorine: 2s1s 2p ↓↑↑↑↑↑↓↓↓ ↓ CoreValance Full Shell – very happy

26 Electronegativity Lets look at Sodium: 2s1s 2p ↓↑↑↑↑↑↓↓↓ CoreValance Empty Shell – very happy 3s ↓↑ 3p

27 Nuclear Charge’s Effect on Electronegativity ↑ Going from Oxygen to Fluorine Orange – Nucleus Blue – core Electrons Red – Valance Electrons Dotted Line – Nuclear influence Electronegativity get greater as we go left to right

28 Nuclear Charge’s Effect on Electronegativity Orange – Nucleus Blue – core Electrons Red – Valance Electrons Dotted Line – Nuclear influence ↑ Going from Neon to Sodium ↑ Electronegativity get less as we go top to bottom

29 Likely Charges for Families Families of Elements have similar electron configurations Lets Look at the Alkali Metals: 2s Li[He] ↑ 3s Na[Ne] ↑ 4s K[Ar] ↑ 5s Rb[Kr] ↑ 6s Cs[Xe] ↑ 7s Fr[Rn] ↑

30 Likely Charges for Families Remember that the electronegativity for these elements is very low (electrons are easily taken by other elements or left behind) If these elements “lose” their valence (or outer) electrons easily, what charge do you think these elements might become?

31 Likely Charges for Families Sodium: 11 protons (+11) & 2s1s 2p ↓↑↑↑↑↑↓↓↓ CoreValance 3s ↓↑ 3p electrons Total Charge: 11(-11)10(-10) 0+1 When Alkalai Metals become ions (a charged element) it will become +1 charged

32 Likely Charges for Families Lets Look at the Halogens: F[He] 2s 2p ↓↑↑↑↑↓↓ Cl[Ne] 3s3p ↓↑↑↑↑↓↓ Br[Ar] 4s4p ↓↑↑↑↑↓↓ I[Kr] 5s5p ↓↑↑↑↑↓↓

33 Likely Charges for Families Chlorine: 17 protons (+17) & 2s1s 2p ↓↑↑↑↑↑↓↓↓ CoreValance 3s ↓ 3p electrons Total Charge: 17(-17)18(-18) 0 When Halogens become ions it will become -1 charged ↑↓↑↓↑↓↑ ↓

34 Likely Charges for Families Nobel Gases Alkaline Earth Metals Halogens Alkali Metals Pnictides Chalcogens ±


Download ppt "Periodic Law The nucleus of the atom exerts forces upon its electrons that make them have distinctive traits or trends. What are these trends and how are."

Similar presentations


Ads by Google