Unit 3 Notes: Periodic Table Notes

[Pages:29]Unit 3 Notes: Periodic Table Notes

? John Newlands proposed an organization system based on increasing atomic mass in 1864.

? He noticed that both the chemical and physical properties repeated every 8 elements and called this the ____Law of Octaves ___________.

? In 1869 both Lothar Meyer and Dmitri Mendeleev showed a connection between atomic mass and an element's properties.

? Mendeleev published first, and is given credit for this. ? He also noticed a periodic pattern when elements were ordered by

increasing ___Atomic Mass _______________________________. ? By arranging elements in order of increasing atomic mass into columns,

Mendeleev created the first Periodic Table. ? This table also predicted the existence and properties of undiscovered

elements. ? After many new elements were discovered, it appeared that a number of

elements were out of order based on their _____Properties_________. ? In 1913 Henry Mosley discovered that each element contains a unique

number of ___Protons________________. ? By rearranging the elements based on _________Atomic Number___, the

problems with the Periodic Table were corrected. ? This new arrangement creates a periodic repetition of both physical and

chemical properties known as the ____Periodic Law___.

Periods are the ____Rows_____ Groups/Families are the Columns

Valence electrons across a period are There are equal numbers of valence

in the same energy level

electrons in a group.

? When elements are arranged in order of increasing _Atomic Number_, there is a periodic repetition of their physical and chemical properties

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? Family (Group): ___Columns (vertical)______; tells the number of electrons in the _Outer___ Energy level, called __Valence Electrons________ (only for representative elements)

? Period (Series): __Rows (horizontal)____; tells the number of ____Energy Levels__________ an atom has; the number of electrons __Increases__ across a period

? Representative Elements: Groups __1A through 8A _ (called the s and p blocks) (Columns 1, 2, 13, 14, 15, 16, 17, and 18)

? Valence Electrons: e- in the ___outer most energy level____; farthest away from the __nucleus (protons)___; the e- with the ___most reactive____ Energy; the e- involved with ___Bonding____ (transferred or shared)

? Metals: most of the periodic table, located to the __Left___ of the "stair-step" Properties- good conductors of _heat_ and _Electricity_; they also are __ Malleable___; __ Ductile____; _ High Density, BP and MP_____

? Nonmetals: to the Right of the "stair-step", located in the upper corner of P.T._ ? Although five times more elements are metals than nonmetals, two of the nonmetals--hydrogen and helium--make up over 99 per cent of the observable Universe ? Properties- mostly _ Brittle __, but a few _low luster______ and _poor conductors__; they have _ low density, low MP and BP__

? Metalloids: also called _semi-metals__, located _along_ the "stair-step" ? Properties - __ similar __ to both metals and nonmetals

? Some metalloids are shiny (silicon), some are not (gallium) ? Metalloids tend to be brittle, as are nonmetals. ? Metalloids tend to have high MP and BP like metals. ? Metalloids tend to have high density, like metals. ? Metalloids are semiconductors of electricity ? somewhere between

metals and nonmetals. This makes them good for manufacturing computer chips.

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Element Symbol Group # # of valence ePeriod # # of E levels Type of element

Lithium Li

1A(1) 1 2 2 M

Germanium Ge

4A(14) 4 4 4 M

Sulfur S

6A(16) 6 3 3 NM

Periodic Trends:

1. Atomic Size - __Decreases__ from left to right across a period (smaller) - __Increases___ from top to bottom down a group (larger)

Why? - as you go across a period, (same __energy level__), e- are _added_but _pulled closer to the nucleus___ - as you go down a group, you add ___energy levels___

2. Ionization Energy: the amount of E needed to _remove / lose_ an electron - __Increases__ from left to right across a period - __Decreases____ from top to bottom down a group

Why?

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- as you go across a period, e- feel stronger attraction from nucleus (protons)___,

_Energy___ to remove e-, ____Ionization___ E necessary as you go down a group, more __Energy_, _Decreases_ to remove outermost e- because they are further away from the Nucleus (protons)

3. Electronegativity: the tendency for an atom to __attract___ electrons; exclude Noble Gases! - __Increases__ from left to right across a period (except Noble Gases) - __Decreases____ from top to bottom down a group

Why? - as you go across a period, e- feel ___more__ attraction from nucleus _Protons_____ to pull in more e- as you go down a group, more _shielding__ from inner e-, __hinders the nucleus ability__ to attract more e-

4. Ionic Size: Cations:__positive_ ions; metal atoms that ___lose__ electrons

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- __smaller__ than corresponding neutral atom Why?

- __fewer__ e-, so it's _easier_ for protons to pull in remaining eAnions:__Negative___ ions; nonmetal atoms that _gain_ electrons

- ___larger____ than corresponding neutral atom Why?

- _more_ e-, so it's __harder_ for protons to pull in outermost eShielding: The ability of the _inner (lower levels)_ electrons to _shield (reduce)_ the pull of the _protons_ on the _outer (higher levels)__ electrons. "Shielding effect"_increase_ as you add Energy levels (move down a group)

Quantum Model Notes

? Heisenberg's Uncertainty Principle- Can determine either the _velocity or the position of an electron, cannot determine both.

? Schr?dinger's Equation - Developed an equation that treated the hydrogen atom's electron as a wave. o Only limits the electron's energy values, does not attempt to describe the electron's path.

? Describe probability of finding an electron in a given area of orbit. ? The Quantum Model- atomic orbitals are used to describe the possible position

of an electron.

Orbitals

? The location of an electron in an atom is described with 4 terms.

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o Energy Level- Described by intergers. The higher the level, the more energy an electron has to have in order to exist in that region.

o Sublevels- energy levels are divided into sublevels. The # of sublevels contained within an energy level is equal to the integer of the energy level.

o Orbitals- Each sublevel is subdivided into orbitals. Each orbital can hold 2 electrons.

o Spin- Electrons can be spinning clockwise (+) or counterclockwise (-) within the orbital.

Periodic Table Activity: Complete the table on page 21 with the information found on pages 18-20. When complete color each group in a different color in the periodic table.

The Periodic Table Notes:

Historical development of the periodic table: Highlights ? Mendeleev (1869): Put the elements into columns according to their properties. Generally ranked elements by increasing atomic mass. ? Moseley (1911): Periodic table arranged by atomic number

Top table: Metals, nonmetals, and metalloids ? Metals: Explain the electron sea theory, and as you explain each of the properties below, discuss how they are explained by the electron sea theory. Also make sure to explain that these are general properties and may not be true for all metals. o Malleable: Can be pounded into sheets. o Ductile: Can be drawn into wires o Good conductors of heat and electricity o High density (usually) o High MP and BP (usually) o Shiny o Hard ? Nonmetals: Explain how the bonds between the atoms are highly localized, causing each of the properties below. Again, emphasize that these are general properties and may not be true for all nonmetals. o Brittle o Poor conductors of heat and electricity o Low density o Low MP and BP (many are gases)! ? Metalloids: The bonding in metalloids is between that of metals and nonmetals, so metalloids have properties of both. o Some metalloids are shiny (silicon), some are not (gallium) o Metalloids tend to be brittle, as are nonmetals. o Metalloids tend to have high MP and BP like metals. o Metalloids tend to have high density, like metals.

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o Metalloids are semiconductors of electricity ? somewhere between metals and nonmetals. This

makes them good for manufacturing computer chips.

Structure of the periodic table

? Families/groups (the terms are synonymous and will be used interchangeably)

o These are elements in the same columns of the periodic table.

o Elements within families/groups tend to have similar physical and chemical properties.

o They have similar chemical and physical properties because they have similar electron

configurations. Example:

Li = [He] 2s1, Na = [Ne] 3s1 ? each has one electron in the outermost

energy level.

o Explain that s- and p-electrons in the outermost energy level are responsible for the reactions

that take place.

Valence electrons: The outermost s- and p-electrons in an atom.

Show them how to find the number of valence electrons for each atom and explain that

they are only relevant for s- and p- electrons. Do several examples.

? Periods: Elements in the same rows of the periodic table o Elements in the same period have valence electrons in the same energy levels as one another. o Though you'd think this was important, it has very little effect on making the properties of the elements within a period similar to one another. The closer elements are to each other in the same period, the closer are their chemical and physical properties.

? Other fun locales in the periodic table: o Main block elements: These are the s- and p- sections of the periodic table (groups 1,2, 13-18) o Transition elements: These are the elements in the d- and f-blocks of the periodic table. The term "transition element", while technically referring to the d- and f-blocks, usually refers only to the d-block. Technically, the d-block elements are the "outer transition elements" Technically, the f-block elements are the "inner transition elements"

Major families in the periodic table: (Show them examples of these elements ? if available ? and color each family as I discuss their properties)

? Group 1 (except for hydrogen) ? Alkali metals o Most reactive group of metals o Flammable in air and water o Form ions with +1 charge o Low MP and BP (MP of Li = 181? C, Na = 98? C) o Soft (Na can be cut with a knife) o Low density (Li = 0.535, Na = 0.968)

? Group 2: Alkaline earth metals o Reactive, but less so than alkali metals o React in air and water (show Ca reacting in water) o Form ions with +2 charge o Low MP and BP, but higher than alkali metals (MP of Ba= 302? C, Mg = 649?C o Soft, but harder than alkali metals o Low density, but higher than that of alkali metals (Ca = 1.55, Mg = 1.74).

? Groups 3-12: (Outer) transition metals o Note: These are general properties and may vary from transition metal to transition metal! There are many exceptions to each of these rules! o Stable and unreactive. o Hard

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o High MP and BP (Fe = 1535? C, Ti = 1660? C). o High density (Fe = 7.87, Ir = 22.4) o Form ions with various positive charges (usually include +2 and several others) o Used for high strength/hardness applications, electrical wiring, jewelry ? Inner Transition Metals: Lanthanides and actinides o Lanthanides (4f section)

Also called the rare earth metals, because they're rare. Usually intermediate in reactivity between alkaline earth metals and transition metals. High MP and BP Used in light bulbs and TV screens as phosphors. o Actinides (5f section) Many have high densities Most are radioactive and manmade Melting points vary, but usually higher than alkaline earth metals. Reactivity varies greatly Used for nuclear power/weapons, radiation therapy, fire alarms. ? Group 13: Boron Group ? Group 14: Carbon Group ? Group 15: Nitrogen Group ? Group 16: Oxygen Group

? Group 17: Halogens o The most highly reactive nonmetals. o Highly volatile ? F and Cl are gases, Br is a volatile liquid, and I is an easily sublimed solid. o Strong oxidizers ? they readily pull electrons from other atoms. o Diatomic ? form molecules with formula of X2 o Form ions with -1 charge o Used in water treatment and chemical production ? Cl2 was used as a chemical weapon in World War I.

? Group 18: Noble Gases o Highly unreactive o Used to provide the atmosphere in situations where you don't want chemical reactions to occur (light bulbs, glove boxes, etc).

? Hydrogen ? "The Weirdo" o Has properties unlike any other element o Diatomic ? H2 o Can form either a +1 or -1 charge o Relatively unreactive unless energy is added (under most conditions) ? it can form explosive mixtures with oxygen (as it did in the Hindenburg explosion)

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