LECTURE 4 THE PERIODIC TABLE

The Periodic Table  Organized by the number of protons (it’s atomic number)  Contains: Atomic number Symbol Name Atomic mass

 Groups Vertical columns ( ↕ ) containing elements with similar properties  Periods Horizontal rows ( ↔ ) with predictable trends The Periodic Table

Most Elements Are Metals, continued The regions highlighted in blue indicate the elements that are metals. Section 2 Tour of the Periodic Table Chapter 4

Metals  On the left of the zig-zag line  Make up most of the P.T.  Have Luster (shiny)  Good conductors of heat and electricity  Malleable (can be shaped)  Ductile (can be made into a wire)  High tensile strength (wires can hold mass)

Visual Concepts Properties of Metals: Malleability and Ductility Chapter 4

Nonmetals  Found to the right of the zig-zag line  INCLUDES HYDROGEN  Many are gases at room temperature  Solids are brittle  Poor conductors of heat & electricity

Metalloids Semi-Metals  Found straddling the zig-zag line  Some properties of metals & nonmetals  Semiconductors of electricity

Visual Concepts Comparing Metals, Metalloids, and Nonmetals Chapter 4

Group Names  Group 1: Alkali Metals  Group 2: Alkaline Earth Metals  Groups 3-12: Transition Metals  Group 17: Halogens  Group 18: Noble Gases  Elements # 58 – 71 Lanthanides  Elements # 90 – 103 Actinides

ELECTRON CONFIGURATIONS REFER BACK TO CHAPTER 3 SECTION 3

ELECTRONS  Found in specific regions – orbital  4 orbitals s (sphere shaped) p (dumbbell shape) d (cross dumbbells) f (don’t ask… it’s complicated)

s Orbitals  Sphere shaped  Can only hold 2 e - total

p Orbitals  Dumbbell shape  3 positions  Each position holds 2 e -  6 e - total

d Orbitals  Cross dumbbell shape or 4 leaf clover shape  5 positions total  Each position holds 2 e -  Holds total 10 e -

f Orbitals  Dumbbell shape surrounded by donut shape  7 positions  Each position holds 2 e -  Holds total of 14 e-

Using the Periodic Table

Using the P.T. to Count #’s s Block

Using the P.T. to Count #’s p Block

Using the P.T. to Count #’s d block

Using the P.T. to Count #’s f Block

 Blocks of the Periodic Table Section 1 How Are Elements Organized? Chapter 4

Writing Electron Configurations  Orbitals must fill in a particular order  The 1 st number indicates the period or level the electron is found in.  The letter indicates the orbital the electron is found in.  The exponent indicates how many electrons are there.

Sample Problem A Write the electron configuration for Sodium, Na.

Sample Problem A Write the electron configuration for Sodium, Na. Step 1: Find the # of electrons (Look at the Atomic number) Na is Atomic # 11. Na has 11 e -

Sample Problem A Write the electron configuration for Sodium, Na. Step 2: Follow the correct ordering and fill orbitals 1s 2 11 – 2 = 9 e - left

Sample Problem A Write the electron configuration for Sodium, Na. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 (9 – 2 = 7 e - left)

Sample Problem A Write the electron configuration for Sodium, Na. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 2p 6 (7 – 6 = 1 e - left)

Sample Problem A Write the electron configuration for Sodium, Na. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 2p 6 3s 1 (1 – 1 = 0 e - left) DONE!

Sample Problem B Write the electron configuration for Argon, Ar.

Sample Problem B Write the electron configuration for Argon, Ar. Step 1: Find the # of electrons (Look at the Atomic number) Ar is Atomic # 18. Ar has 18 e -

Sample Problem B Write the electron configuration for Argon, Ar. Step 2: Follow the correct ordering and fill orbitals 1s 2 18 – 2 = 16 e - left

Sample Problem B Write the electron configuration for Argon, Ar. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 (16 – 2 = 14 e - left)

Sample Problem B Write the electron configuration for Argon, Ar. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 2p 6 (14 – 6 = 8 e - left)

Sample Problem B Write the electron configuration for Argon, Ar. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 2p 6 3s 2 (8 – 2 = 6 e - left)

Sample Problem B Write the electron configuration for Argon, Ar. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 2p 6 3s 2 3p 6 (6 – 6 = 0 e - left)

Sample Problem C Write the electron configuration for Bromine, Br.

Sample Problem C Write the electron configuration for Bromine, Br. Step 1: Find the # of electrons (Look at the Atomic number) Br is Atomic # 35. Br has 35 e -

Sample Problem C Write the electron configuration for Bromine, Br. Step 2: Follow the correct ordering and fill orbitals 1s 2 (35 – 2 = 33 e - left)

Sample Problem C Write the electron configuration for Bromine, Br. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 (33 – 2 = 31 e - left)

Sample Problem C Write the electron configuration for Bromine, Br. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 2p 6 (31 – 6 = 25 e - left)

Sample Problem C Write the electron configuration for Bromine, Br. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 2p 6 3s 2 (25 – 2 = 23 e - left)

Sample Problem C Write the electron configuration for Bromine, Br. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 2p 6 3s 2 3p 6 (23 – 6 = 17 e - left)

Sample Problem C Write the electron configuration for Bromine, Br. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 (17 – 2 = 15 e - left)

Sample Problem C Write the electron configuration for Bromine, Br. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 (15 – 10 = 5 e - left)

Sample Problem C Write the electron configuration for Bromine, Br. Step 2: Follow the correct ordering and fill orbitals 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 (5 – 5 = 0 e - left) DONE!

Your turn … Writing Electron Configurations #1

Writing Noble Gas Configurations A Short Cut

Noble Gas Configurations  Rules Find the noble gas tha appears BEFORE the element Following the usual order, write the remaining electrons contained in the element’s period  Confusing…but you’ll get it.  DON’T USE THE BACK OF YOUR TEXT!  The ordering is incorrect and I’ll know you cheated!! =(

Sample Problem C Write the noble gas configuration for Sodium. Step 1: Find the noble gas BEFORE sodium. Ne appears before Na. [Ne]

Sample Problem C Write the noble gas configuration for Sodium. Step 2: Follow the ordering, starting at the period Na appears in. Na is in Period 3 [Ne] 3s

Sample Problem C Write the noble gas configuration for Sodium. Step 3: Keep going until you reach Na. Only 1 step, so …. [Ne] 3s 1

Sample Problem D Write the noble gas configuration for Bromine. Step 1: Find the noble gas BEFORE Br. Ar appears before Br. [Ar]

Sample Problem D Write the noble gas configuration for Bromine. Step 2: Follow the ordering, starting at the period Br appears in. Br is in Period 4 [Ar] 4s

Sample Problem D Write the noble gas configuration for Bromine. Step 3: Keep going until you reach Br. [Ar] 4s 2

Sample Problem D Write the noble gas configuration for Bromine. Step 3: Keep going until you reach Br. [Ar] 4s 2 3d 10

Sample Problem D Write the noble gas configuration for Bromine. Step 3: Keep going until you reach Br. [Ar] 4s 2 3d 10 4p 5

Sample Problem E Write the noble gas configuration for Chromium, Cr. Step 1: Find the noble gas BEFORE Cr. Ar appears before Cr. [Ar]

Sample Problem E Write the noble gas configuration for Cr. Step 2: Follow the ordering, starting at the period Cr appears in. Cr is in Period 4 [Ar] 4s

Sample Problem C Write the noble gas configuration for Cr. Step 3: Keep going until you reach Cr. [Ar] 4s 2

Sample Problem E Write the noble gas configuration for Cr. Step 3: Keep going until you reach Cr. [Ar] 4s 2 3d 4

Your turn … Writing Noble Gas Configurations #1

Valence Electron Configurations The REALLY Short way.

Valence Electron Configurations  Rules: Do everything you did with Noble Gas configurations….. EXCEPT DON’T WRITE THE NOBLE GAS!

For example: Hydrogen, H  Look at your periodic table  Hydrogen is: Period 1 s block Only 1 electron  Electron configurations: 1s 1 Writing Valence Electron Configurations

What is the valence configuration for Selenium, Se. Start at the period… Writing Valence Electron Configurations 4s 2 3d 10 4p 4

Your Turn … Writing Electron Configurations & Valence Configurations #1

TRENDS IN THE PERIODIC TABLE

Let’s Review  Group 1 Alkali Metals Ends in s 1 Soft, silvery metals Highly reactive Low density & melting point

Let’s Review  Group 2 Alkaline Earth Metals Valence shell is s 2 Denser, harder, stronger than Alkali Metals Less reactive than alkali metals

Let’s Review  Groups 3 – 12 Transition metals Elements are a little less predictable

Let’s Review  Metalloids Along the staircase starting in Group 13 Valence levels  p orbital Share properties of metals & nonmetals Referred to as semimetals Used as semiconductors in electronics

Let’s Review  Group 17 Halogens Valence level is s 2 p 5 Highly reactive NONmetals Forms salts when combined with Group 1 or 2 metals

Let’s Review  Group 18 Noble Gases Valence level is s 2 p 6 Usually unreactive

And finally ….  Lanthanides (f-block) Top Row of f-block Shiny metals similar to Group 2  Actinides Bottom Row of f-block Naturally radioactive elements

What are the trends?

Atomic Radius Down a group Increases Adding on extra electron orbitals Stacking orbitals keep getting bigger Across a period Decreases More protons become ATTRACTED to more electrons

Atomic Radius, continued Section 3 Trends in the Periodic Table Chapter 4

Ionization Energy  Atom’s ability to steal an e -  Decreases down a group  Increases across a period Increases Decreases

Ionization Energy, continued Section 3 Trends in the Periodic Table Chapter 4

Electronegativity  Atom’s ability to attract an e -  Decreases down a group  Increases across a period Increases Decreases

Electron Affinity  Atom’s ability to accept an e -  Decreases down a group  Increases across a period Increases Decreases

NUCLEAR REACTIONS

Visual Concepts Nuclear Reaction Chapter 4

Visual Concepts Nuclear Fusion Chapter 4

Natural Elements, continued Other Elements Form by Nuclear Reactions in Stars Section 4 Where Did the Elements Come From? Chapter 4