Electromagnetic Spectrum and Atomic Theory Quiz

Electromagnetic Spectrum

• The electromagnetic spectrum (energy spectrum) displays wavelengths of electromagnetic radiation.
• The visible spectrum ranges from 700 to 400 nanometers (nm).
• ROYGBIV represents the colors of the visible spectrum: Red, Orange, Yellow, Green, Blue, Indigo, and Violet.

### Atomic Spectrum

• When light from a heated element is passed through a prism, it separates into distinct lines of color, forming an atomic spectrum.
• Dark areas between these lines are called atomic spectra.
• Each element has a unique atomic spectrum.

Flame Test

• Different elements emit different colors when heated in a flame.
• The flame test is used to identify unknown elements.

Electron Energy Levels

• Electrons in an atom occupy specific energy levels, which are represented by principal quantum numbers (n).
• As the value of n increases, the energy level increases, meaning the electrons are farther from the nucleus.
• Electron energy is quantized, meaning it can only exist at specific energy values.

### Changes in Electron Energy Levels

• Electrons absorb energy to move to a higher energy level.
• When electrons fall back to a lower energy level, light is emitted.
• The energy absorbed or emitted is equal to the difference in energy between the two levels.

Group Number and Valence Electrons

• The group number on the periodic table determines the number of valence electrons an element has.
• Group 1A has 1 valence electron, Group 2A has 2, Group 3A has 3, and so on, up to Group 8A with 8 valence electrons.

Electron-Dot Symbols

• Electron-dot symbols, also known as Lewis structures, represent valence electrons as dots around the element's symbol.

Atomic Size

• Atomic size is determined by the atom's atomic radius, the distance between the nucleus and the outermost electrons.
• Atomic size generally increases down a group on the periodic table because there are more electron shells.
• Atomic size decreases across a period on the periodic table because the number of protons increases, causing a stronger pull on the electrons.

Protons and Neutrons in Atoms

• The number of protons in an atom is its atomic number, and this number determines the element.
• The mass number represents the total number of protons and neutrons in an atom's nucleus.
• The number of neutrons can be calculated by subtracting the atomic number from the mass number.

### Isotopes

• Isotopes are atoms of the same element but have different mass numbers.
• They have the same number of protons but different numbers of neutrons.
• Isotopes can be distinguished by their atomic symbols.
• For example, carbon-12 and carbon-14 are isotopes, both with 6 protons but carbon-12 has 6 neutrons and carbon-14 has 8.