Payton's Pre-AP Chemistry Blog: PeriodicTrends

Energy Levels Change the Color

When you heat an atom, some of its electrons are "excited* to higher energy levels.
When an electron drops from one level to a lower energy level, it emits a quantum of energy.
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The wavelength (colour) of the light depends on the difference in the two energy levels.
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We can see only those transitions that correspond to a visible wavelength.
In a hydrogen atom, for example, we can see only the transitions from higher levels to n = 2 .

As	Arsenic	Blue
B	Boron	Bright green
Ba	Barium	Pale/Yellow-green
Ca	Calcium	Orange-red
Cu (I)	Copper (I)	Blue
Cu (II)	Copper (II) non-halide	Green
Cu (II)	Copper (II) halide	Blue-green
Fe	Iron	Gold
In	Indium	Blue
K	Potassium	Light purple to red
Li	Lithium	Deep pink to dark red
Mg	Magnesium	Bright white
Mn (II)	Manganese (II)	Yellow-green
Mo	Molybdenum	Yellow-green
Na	Sodium	Bright yellow
P	Phosphorous	Pale blue-green
Pb	Lead	Blue
Rb	Rubidium	Red/Purple-red
Sb	Antimony	Pale green
Se	Selenium	Bright blue
Sr	Strontium	Crimson
Te	Tellurium	Pale green
Tl	Thallium	Bright green
Zn	Zinc	Blue-green to pale green

Absorbency

https://drive.google.com/open?
id=0B6biT3nsiazTaDRxTGx1MW9CdGM

This is our lab activity that we measured absorbency and and transmitted. This lab was long and extensive but overall was very informative. I enjoyed how simply the procedure was and doing stuff on excel.

It's Lit

https://drive.google.com/open?id=0B6biT3nsiazTNkI1UnpsZjBaLW8

https://drive.google.com/open?id= 0B6biT3nsiazTcDBvZnN4YkpIQlE

This is our identifying the mystery metal was probably the best lab we've done so far. It was so fascinating how different metals produce different colors when burned. The colors were pretty as well . I wish we had more labs like this.

Trend Setters

Density Trends:
The density of an element is the amount of mass it has per unit volume. Normally this is measured in g cm⁻³ and at room temperature. Values are shown relative to osmium, the element with the highest density.

Atomic Radius trends:
The non-bonded atomic radius of an atom is half of the distance between two unbonded atoms of the same element when the electrostatic forces are balanced. Atoms are not well defined spheres so there are many ways of calculating atomic radius. Values are shown relative to francium, the element with the highest atomic radius.

Electronegativity trends:
The electronegativity of an atom is how strongly it attracts electrons towards itself. It depends on the atomic radius and the atomic number of the element. Electronegativity is most commonly measured on the Pauling scale. Values are shown relative to fluorine, the element with the highest electronegativity.

Melting Point Trends:
The melting point of an element is the temperature at which the solid–liquid phase change occurs. Values are shown relative to the sublimation point of carbon, the highest temperature at which any element remains solid.

Ionization Energy trends:
The first ionisation energy of an atom is the minimum energy required to remove an electron from a neutral atom in its ground state. Values are shown relative to helium, the element with the highest first ionisation energy.