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Chapter 4, Lesson 3 Multimedia

Energy Level Cross Section

A two-dimensional (flat) representation of the energy levels that surround the nucleus of an atom and in which electrons can be found.A three-dimensional representation of the spherical energy levels that surround the nucleus of an atom and in which electrons can be found.
  • Electrons are in regions around the nucleus that are different distances away from the nucleus.
  • The electrons surround the nucleus in 3 dimensions but it is easier to show an energy level model in two dimensions like the model that looks like a target.

Oxygen Atom

A depiction of an oxygen atom, showing a large dot representing the nucleus in the center, and smaller dots in two coencentric circles, representing the energy levels of oxygen.
  • This energy level model shows two electrons on the first energy level and six electrons on the second energy level.
  • Since this atom has a total of eight electrons, it also has eight protons.
  • The atom with eight protons in its nucleus (atomic number 8) is oxygen.

Periodic Table of Energy Levels

A truncated periodic table, showing elements 1–20, and their distribution of electrons through their corresponding energy levels.
  • Each energy level holds a certain number of electrons before electrons go into the next level.
  • 1st Period: Hydrogen and helium—Electrons go into the first energy level. After the first level has two electrons, the next electron goes into the second level.
  • 2nd Period: Lithium to neon—Electrons go into the second level. After the second level has 8 electrons,the next electron goes into the third level.
  • 3rd Period: Sodium to argon—Electrons go into the third energy level. After the third energy level has 8 electrons, the next electron goes into the fourth level.
  • 4th Period: Potassium and Calcium—Electrons go into the fourth energy level.

Sodium in Water

This video shows that potassium reacts violently when placed in water. It skids around on the surface of the water until it is cosumed.

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  • A small piece of sodium metal is placed in water.
  • The sodium reacts with the water and gets very hot, producing sodium hydroxide and hydrogen gas. The demonstration shown in this video is very dangerous. Do not attempt to perform this demonstration.

Potassium in Water

Potassium reacts with water even more vigorously than sodium. The potassium evolves flames and moves violently when in contact with water.

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  • A small piece of potassium metal is placed in water.
  • The potassium reacts with the water and gets very hot, producing potassium hydroxide and hydrogen gas which ignites.
  • The reaction of the potassium with water is similar to the reaction of sodium in water but hotter. The demonstration shown in this video is very dangerous. Do not attempt to perform this demonstration.

Calcium in Water

When calcium is placed in water it bubbles vigorously.

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  • Small pieces of calcium are placed in water.
  • The calcium reacts with the water but does not get nearly as hot as either the sodium or potassium.
  • Also, the calcium hydroxide produced forms a white solid in the solution which is different from the sodium or potassium.
  • Hydrogen gas is also produced. The demonstration shown in this video is very dangerous. Do not attempt to perform this demonstration.

Sodium in Acid

When sodium is placed in two different acids (hydrochloric and nitric acid) at two different concentrations, it reacts strongly with each, producing flame and smoke.

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  • Small pieces of Solid sodium metal are placed in two different concentrations of two different acids (hydrochloric acid and nitric acid).
  • The sodium reacts most vigorously with the nitric acid, producing a flame and smoke.
  • The sodium also reacts pretty strongly with the weaker concentration of hydrochloric acid. The demonstration shown in this video is very dangerous. Do not attempt to perform this demonstration.

Potassium in Acid

When potassium is placed in two different acids (hydrochloric and nitric acid) at two different concentrations, it reacts strongly with each, producing flame and smoke. This is similar to how sodium responds to the same acids at the same concentrations.

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  • Small pieces of solid potassium metal are placed in two different concentrations of two different acids (hydrochloric acid and nitric acid).
  • The potassium reacts most vigorously with the nitric acid, producing a flame and smoke, similar to the sodium.
  • The potassium also reacts pretty strongly with the weaker concentration of hydrochloric acid, similar to the sodium. The demonstration shown in this video is very dangerous. Do not attempt to perform this demonstration.

Calcium in Acid

When calcium is placed in two different acids (hydrochloric and nitric acid) at two different concentrations, it bubbles vigorously, but does not react as violently as Potassium or Sodium.

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  • Small pieces of solid calcium metal are placed in two different concentrations of two different acids (hydrochloric acid and nitric acid).
  • The calcium reacts most vigorously with the hydrochloric acid, producing bubbles.
  • The reaction between calcium and the acids does not get as hot as between sodium or potassium with the acids. The demonstration shown in this video is very dangerous. Do not attempt to perform this demonstration.