Electromagnetic Spectrum

Bohr’s Model of the Atom

Electromagnetic Spectrum: different types of energy that travel in waves

•the wave pattern is made of electric and magnetic fields that can travel through empty space

•ex: UV rays, microwaves, visible light

•type of energy depends on frequency & wavelength

• frequency = how often a wave repeats itself in 1s represented by , measured in Hz

• wavelength = distance between 2 crests or 2 troughs– represented by (Greek symbol lamda), measured in meters– wavelength of visible light is usually measured in nanometers (nm) =

10-9 m

How are and related?

• the shorter the , the higher the (the more the wave contains)

• the longer the , the lower the (the less the wave carries)

• longer are safe for humans, short can be harmful– this is why radio waves are safe but X-rays are not

Visible Light

Low Energy

High Energy

• continuous spectrum : a spectrum in which all the wavelengths of light are represented in an uninterrupted sequence

• ex: white light, which is real light that we see

• it’s a bunch of colours smeared together

• line spectrum = distinct colour lines rather than white light, unique to each element

• aka discontinuous spectrum• each of the bands represents one jump

of an electron

Why??

• each element gives off their own distinct bands of colour– the bands appear in the sections that correspond

to various elements

Hydrogen

Carbon

The Bohr Model of the Atom

•Electrons travel in orbits

•Orbits are at fixed distances

•Electrons will continue on their path until told to do otherwise. (Energy)

Elements and their Colours

•e– can become excited and can “jump” to a higher shell•when the E is removed, the excited e– “falls” back down to its ground state and releases its E in the form of light

• spectroscope = instrument that separates light into its component bands of colour

• uses a prism or a diffraction grating• we use them to identify elements contained in

a substance (ex: stars)• we can also tell if a body in space is moving

towards us or moving away