Elements & Atoms

Physical Science1/23/2012 – 1/26/2012

What is an element?

An element is the simplest type of substance (material made of one kind of matter).

An element can't be broken down into anything simpler by ordinary physical or chemical methods.

Compounds are mixtures or combinations of elements.

What are element symbols?

Element symbols are a useful AND universal way to abbreviate the name of an element.

A chemical symbol has one, two, or three letters, taken from the name of the element it represents (either English or Latin).

The first letter in a symbol isalways capitalized and any otherletter is always lowercase.

Matching – In NotesELEMENT SYMBOL

Oxygen Hg

Zinc Al

Nitrogen Ca

Gold C

Magnesium O

Copper Zn

Aluminum Au

Carbon N

Mercury Cu

Calcium Mg

Match each element on the left to its symbol on the right.

Why do you think the symbol is not always the first letter or two letters of the element name?

Which symbols were the hardest to match & why?

HW due Tuesday, January 24Your job for homework is to create an

element trading card for one of the following elements.

You must include atomic number & atomic mass, number of protons, neutrons, & electrons, discovery

information, and important uses (EC for a picture on the back of your card).

Use the template provided to make your trading card.

Element choices: Hydrogen, Carbon, Oxygen, Calcium, Sodium, Iron, Lead,

Aluminum, Copper, Zinc, Nitrogen, Gold, Mercury

Tuesday, January 24

Bell Ringer: What do you know about atoms? What are the parts of an atom and what do you know about each part?

Atoms

An atom is divided into two different areas: the nucleus and the electron shells.

In the nucleus, you can find protons and neutrons.

A proton is a particle that is heavy (for an atom) and has a positive charge. Remember, “pro” means positive.

A neutron is a particle that is heavy (for an atom) and has no charge. Remember, “neutr-” means neutral or no charge.

Nucleus

Protons and neutrons are locatedin the nucleus of an atom.

The atomic number of an atomis the number of protons orelectrons in that atom.

The atomic mass of an atom is the number of protons + the number of neutrons.

What is the atomic number of the atom shown?

What is the atomic mass of the atom shown?

Electrons Electrons are located outside the nucleus in

what are called electron shells. They are light and have a negative charge.

You can think of electron shells as a series of rings outside the nucleus.

The shell closest to the nucleus has the lowest energy and is called the ground state.

The farther away you get from the nucleus, the more energy the electrons have.

For a neutral atom, the # of electrons = the # of protons.

In-Class Assignment On Atoms

You know that atomic # = # of protons or electrons and atomic mass = # of protons + # of neutrons.

Use this to fill out your worksheet for 6 elements and TURN IN at the end of class.

Wednesday, January 25

Intro to Spectroscopy

Spectroscopy is the analysis of light interacting with matter.

We are going to look at the emission spectra of different metals in order to help us identify the metal and describe the structure of atoms inside that metal.

Prism & Light Waves

When white light passes through a prism, it produces a rainbow of colors.

When light emitted from an element is passed through a prism, you see specific lines of colors

Light Waves

Waves travel and transfer energy in an oscillating fashion (they wiggle).

The amplitude, y, of a wavedescribes its height fromzero to a crest.

The wavelength, λ, of a wave is the distance between crests.

Waves & Energy

If both waves travel at the same speed, which one would have more complete wave cycles passing a point in a given time interval?

Since waves transfer energy, which one has more energy?

Higher frequencies have higher energy & lower wavelength.

shorter

shorter

Waves & Energy

Why do atoms emit light?

An atom has a specific arrangement of electrons in valence shells (like we talked about yesterday).

If you add energy to an atom, the electrons will absorb energy, get excited, and move farther away from the nucleus.

Electrons LIKE being in their ground state, so they return to the ground state by emitting light (photons).

Frequency or color of emitted light is proportional to the energy change of the electron (red light = less energy)

HW due Thursday, January 26

Complete the “Wave HW” assignment based on today's notes.

Thursday, January 26

Bell Ringer: What does the ladder & marker demo have to do with atoms and light?

Emission Spectrum

When a glowing gas (like a heated metal in a flame test) radiates energy at specific wavelengths depending on the element(s) present in your sample.

The emission spectrum of something shows the energy levels that electrons are jumping down from (each line is a different level).

The emission spectrum of asample is like its fingerprint –unique to that sample.

Emission Spectrum DEMO

http://phet.colorado.edu/en/simulation/discharge-lamps

What do you notice or observe about the emission spectrum of ONE of the elements? Are the lines close together or far apart? Is there just one line or are there many?

Compare two of the elements.