standard 2 1. energy changes in the atom specific to the movement of electrons between energy levels...

Standard 2 1. energy changes in the atom specific to the movement of electrons between energy levels in an atom resulting in the

emission or absorption of quantum energy. 2. emission of high-energy particles results from nuclear

changes 3. that matter can be converted to energy during nuclear

reactions.

2.1

Evaluate quantum energy changes in the atom in terms of the energy

contained in light emissions.

• A. What is the relationship between wavelength and energy? What would the graph look like?

• Increase - Decrease

Visible light • least Energy and the longest wavelength?• Red• Most Energy and the shortest wavelength?• Violet

Hint:ROYGBIV

Hint:ROYGBIV

ROY GIV

• Red = lower energy because Roy is a lazy boy

• Violet = higher energy

• Remember energy and wavelength are opposites.

b. Lab evidence energy, electrons and energy levels?

• What happens to an electron when it is excited?

• It jumps to a higher energy level – absorbing a quanta (amount) of energy.

• What happens when it falls back down to its ground state?

• It emits light of a specific wavelength (color)

• When elements are heated or electrically excited, they may give a line spectrum.

• They absorb only certain amounts of energy, or quanta. Then energy as the electron falls back down.

Each element has its own set of lines. Analyzing lines from distant stars tell us what elements are present in the star.

• The reason that the images are lines is that the light from the lamp is focused on a narrow slit. The illustration shows the separation of a light beam into its component colors

Unknown

Flame test

• Works in the same way to identify some elements.

Barium Calcium Sodium RubidiumWhat is the unknown?

Put these in order from lowest to highest Energy.

2.2

Nuclear Reactions

Changes in the nucleus of an atom result in emission of radioactivity. --

Radioactive means unstable

Can matter be converted to energy?

• Yes but only in nuclear reactions

Fission Reactions

• Fission occurs when atoms split, ex nuclear bombs.

Fusion reactions

• Fusion occurs when atoms combine to form bigger atoms. Ex. hydrogen turns into helium in the sun.

Elements with unstable nucleus will become stable by emitting?

• Particles – The most common are are α, β and γ.

alpha (helium nucleus) emission:

• U⟶He + Th (stopped by paper)

beta (electron) emission

• C N + ⟶ e

gamma emission:

• Tc-m Tc + ⟶ γ (stopped by lead)

Put in order of mass. From least to greatest.

Gama y Beta , Alpha ,

Hint: – Alpha is a Helium, Beta is an electron

Put in order of penetrating power. From least to greatest.

Alpha , Beta , Gama y

Hint: – Alpha is a Helium, Beta is an electron

Put in order of Energy . From least to greatest.

Alpha , Beta , Gama y

Hint: – Alpha is a Helium, Beta is an electron

Same as penetrating power

2.2.3 Symbol

Actual

Mass

Penetrating Power

Energy

α 4 Little (Paper stops)

Low

β ~0 Medium

Medium

γ 0 High (5 ft concrete)

Very High

What are the effects of radiation?

Good Bad

Radioactive – the good

• Tracer - To identify and diagnose

• The medicine, iodine 131, is a proven cancer fighter.

• But it's also radioactive, and in higher doses, can cause cancer

What are the dangers of radiation?

• small doses may burn tissue, disable cell division and the immune system.

Small doses over time may cause cancer and genetic defects.

Large doses• Death from radiation

sickness is often by dehydration because the digestive tract is damaged.

Marie Curie

• Discovered radiation but eventually died from it.

Turtles exposed to radiation

What is the difference between nuclear reactions and chemical

reactions?• Nuclear reactions involve changes in the

nucleus.• Chemical reactions involve valence (outer shell

electrons.

What is the difference between Energy produced in nuclear

reactions and chemical reactions?• Nuclear Reactions produces much higher

amounts of energy

What is half life?

• The time it takes for half of an unstable element to decay.

• How do we use this?• To determine the age of a substance –

radiometric/ radioactive or carbon dating

What is the concentration at 200 years?

•

• How many years old is this when 20 % of the strontium is left?