Periodic Trends Vocabulary:
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Periodic Trends Vocabulary:

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Periodic Trends Vocabulary:




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Presentation on theme: "Periodic Trends Vocabulary:"— Presentation transcript:

Slide1

Periodic Trends

Vocabulary:metalnonmetalmetalloidmalleableductileatomic radiuselectronegativityionization energyshielding

“Wolfram”,

Viza

Arlington, 2010

Slide2

Trend

What is a trend?a pattern or direction

Starbucks Stock History

Slide3

Periodic trends

The elements have trends, too. For example:Look at the zig-zag line on your periodic table. Metals are on the left, nonmetals on the right, and the metalloids are adjacent to the line.

Metals

Nonmetals

Metaloids

Slide4

Important side-note

Metalsshinygood conductors of electricity and heathardmalleableductilegive away electronsNonmetalsdullgood insulatorsbrittle

accept electrons

Metalloids

some properties of metals and some of nonmetals

Slide5

Important side-note

MetalsNonmetals

sulfur

bromine

carbon

Slide6

Important side-note

MetalNonmetal

Slide7

Periodic Trends

We’re going to look at trends on the periodic table for physical properties of elements. These are:atomic radiuselectronegativityionization energy

Slide8

Atomic Radius

Distance from the nucleus of an atom to the outermost electrons.Typically measured as half the distance between the nuclei of identical bonded atoms.The range is about 25 pm for the smallest atoms to about 250 pm for the largest atoms

Slide9

Electronegativity

The ability of an atom in a chemical compound to attract valence electrons. The scale is from 0-4 with 0 meaning no attraction for valence electrons and 4 as the highest attraction.

Slide10

Electronegativity

What do you think would affect the ability of an atom to attract electrons?Number of protons in the nucleus and distance of electron from nucleusWhen an atom gains or loses an electron, the atom is called an ion.

This is a negative ion because it gained an extra negative electron.

Slide11

Ionization Energy

The energy required to remove one electron from a neutral atom of an element.What do you think would affect the amount of energy required to remove an electron?Number of protonsDistance from nucleus

This is a positive ion because it lost an electron.

Slide12

Periodic Trends

You will now look at trends on the periodic table for atomic radius, electronegativity, or ionization energy.To do this, you will pick one of the following options and use Open Office to make two graphs:Option 1Atomic Radius values of group 1.Atomic Radius values of period 4.Option 2Electronegativity values of group 1.Electronegativity values of period 4.Option 3Ionization energy values of group 1.

Ionization energy values of period 4.

Slide13

Questions

What trend do you see on each graph as you move across a period?What trend do you see on each graph as you move down a family?

Slide14

Atomic Radius Trends

Decreasing Atomic Radius Increasing Atomic Radius 

Slide15

Electronegativity Trends

Increasing ElectronegativityDecreasing Electronegativity

Slide16

Ionization Energy Trends

Increasing Ionization EnergyDecreasing Ionization Energy

Slide17

Why?

Why do these trends exist? Let’s take a look first at the elements in group 1 to find out about the trends in families.

Slide18

Group 1

Shielding

: the blocking of the nuclear charge to the valence electrons by the core electrons. More energy levels = more shielding. (Valence electrons are circled.)

Two consequences of more shielding:

1) Less attraction to outer electrons by nucleus (lower electronegativity);

2) Easier to remove electrons from valence shell (lower ionization energy).

Slide19

Why?

Now let’s look at some of the atoms in period 4.

Slide20

Period 4

The number of protons increases as you go across a period, yet the shielding does not increase. More protons = more attraction of the electrons to the nucleus.

More attraction of electrons to nucleus = higher electronegativity, higher ionization energy, and smaller atomic radius.

K Ca Sc Ti V Cr