YOYO: What element is this? How do you know?

YOYO: What element is this? How do you know? Argon THERE ARE 18 ELECTRONS – WE KNOW THAT IS Ar BECAUSE THE ATOMIC NUMBER IS 18 AND BECAUSE IT IS NEUTRAL, THE # PROTONS = THE # OF ELECTRONS Ar

Aim: What happens when an electron gets excited? Scanlon

How Can You Tell if an Electron is Excited? 2-4 2-3-1 2-8-2 2-8-4 2-8-4-1 Not excited Carbon Excited Carbon Not excited Magnesium Not excited Silicon Excited Phosphorus

Excited State vs. Ground State EC: 2-8-6 Excited State EC: 2-7-7

How is chemistry involved with these lights? An electric current passing through the gas in each glass tube makes the gas glow with its own characteristic color. The electric current excites the electrons in the gas, and when the electrons return to the ground state they emit energy in the form of light.

The Nature of Light Light is a part of the electromagnetic spectrum radiant energy composed of gamma rays, X-rays, ultraviolet light, visible light, etc. The energy of the electromagnetic spectrum moves through space as waves

Nature of Light Sunlight consists of light with a continuous range of wavelengths and frequencies. When sunlight passes through a prism, the different frequencies separate into a spectrum of colors. In the visible spectrum, red light has the longest wavelength and the lowest frequency.

Less Energy More Energy

Atomic Spectra When atoms absorb energy, their electrons move to higher energy levels. These electrons lose energy by emitting light when they return to lower energy levels. The excitation fallback theory explains the visible emission (bright line) spectrum of element A ground state for the electrons in an atom is an energy state of lowest energy (electron configuration in periodic table) An excited state is an energy state of higher energy

Atomic Spectra Energy absorbed by the electron to go the excited state is equal to energy released or emitted by the electron upon returning to ground state.

Emission Spectrum A prism separates light into the colors it contains. White light produces a rainbow of colors.

Emission Spectrum Light from a helium lamp produces discrete lines. Excited hydrogen atoms emit a pinkish glow. When the visible portion of the emitted light is passed through a prism, it is separated into specific wavelengths that are part of the hydrogen’s line emission spectrum.

Emission Spectrum The wavelengths of the spectral lines are characteristic of the element, and they make up the atomic emission spectrum of the element. No two elements have the same emission spectrum. The fingerprints of an element.

Emission Spectrum of a Mixture of Elements The emission spectrum of a mixture of gases will be a combination of the individual gases in that mixture.

Energy of Light Light can be described as a quanta, or packet, of energy that behaves as if they were particles. Light quanta are called photons. The energy associated with a certain frequency of light is related by the equation: h = 6.63 X 10-34 Js

Before You Leave Check Point For the following configuration: 2-8-18-6 a.) Identify the element b.) Propose an excited state