Introduction to Excited Elements Lab

ACOS 3.0 Use the periodic table to identify periodic trends, including atomic radii, ionization energy,

electronegativity, and energy levels.ACOS 3.3 Utilizing benchmark discoveries to

describe the historical development of atomic structure, including photoelectric effect, absorption,

and emission spectra

Introduction

• Scientists observed that certain elements emitted visible light when heated in a flame.

• Analysis revealed the element’s chemical behavior is related to the arrangement of electrons in its atom.

– Visible Light: A form of electromagnetic radiation.

Electromagnetic Spectrum

• Contains all forms of electromagnetic radiation.

• The only differences in the forms are their wavelength & frequency.

Atomic Emission Spectra

• The set of frequencies of electromagnetic waves emitted by atoms of the element.

• Consists of several individual lines (Bands) of color

• Each element’s atomic emission spectrum is unique

• This spectrum can be used to determine what element you are viewing

Ground State

• Ground State- the lowest allowable energy state of an atom. n=1 (The atom does not radiate energy)– When energy is added to the atom it goes up to a

higher-energy orbital such as n=2

• Up to 7 energy levels have been found for the hydrogen atom. Meaning n values can range from 1-7.

Energy Levels

• The smaller the electron’s orbit, the lower its energy state, or level.

• Each energy level has a quantum number, n, applied to it. (ladder rungs)

What causes this light?

•As electrons absorb energy they become excited and move to higher energy levels. •This energy is released in set amounts of energy (quanta) as the electrons fall back into lower energy levels.

•This energy is released in many regions of the electromagnetic spectrum, including the visible region that you can see.•Quanta of light energy is called photons.

- Electrons of atoms can be excited in various ways including: heat, electricity, and friction.

Spectral lines are created by energy released as an electron moves from an excited state to a lower state.

-Spectral lines are created by energy released as an electron moves from an

excited state to a lower state.

References

• http://www.antonine-education.co.uk/physics_gcse/Unit_1/Topic_5/em_spectrum.jpg