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Published byRandolf Mosley Modified over 9 years ago
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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.
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2.1 Evaluate quantum energy changes in the atom in terms of the energy contained in light emissions.
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A. What is the relationship between wavelength and energy
A. What is the relationship between wavelength and energy? What would the graph look like? Increase - Decrease
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Visible light least Energy and the longest wavelength? Red
Most Energy and the shortest wavelength? Violet Hint: ROYGBIV Hint: ROYGBIV
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ROY GIV Red = lower energy because Roy is a lazy boy
Violet = higher energy Remember energy and wavelength are opposites.
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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)
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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.
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Each element has its own set of lines
Each element has its own set of lines. Analyzing lines from distant stars tell us what elements are present in the star.
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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
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Unknown
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Flame test Works in the same way to identify some elements.
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Put these in order from lowest to highest Energy.
Barium Calcium Sodium Rubidium What is the unknown? Put these in order from lowest to highest Energy.
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2.2 Nuclear Reactions Changes in the nucleus of an atom result in emission of radioactivity. -- Radioactive means unstable
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Can matter be converted to energy?
Yes but only in nuclear reactions
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Fission Reactions Fission occurs when atoms split, ex nuclear bombs.
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Fusion reactions Fusion occurs when atoms combine to form bigger atoms. Ex. hydrogen turns into helium in the sun.
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Elements with unstable nucleus will become stable by emitting?
Particles – The most common are are α, β and γ.
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alpha (helium nucleus) emission:
U⟶ 𝟒 𝟐 He Th (stopped by paper)
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beta (electron) emission
14 6 C ⟶ N + 𝟎 −𝟏 e
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gamma emission: 95 43 Tc-m ⟶ Tc + 𝟎 𝟎 γ (stopped by lead)
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Put in order of mass. From least to greatest.
Hint: – Alpha is a Helium, Beta is an electron Gama y Beta , Alpha ,
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Put in order of penetrating power. From least to greatest.
Hint: – Alpha is a Helium, Beta is an electron Alpha , Beta , Gama y
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Put in order of Energy . From least to greatest.
Hint: – Alpha is a Helium, Beta is an electron Same as penetrating power Alpha , Beta , Gama y
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Symbol Actual Mass Penetrating Power Energy α 𝟐 𝟒 𝑯𝒆 4 Little (Paper stops) Low β −𝟏 𝟎 𝒆 ~0 Medium γ 𝟎 𝟎 𝛄 High (5 ft concrete) Very High
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What are the effects of radiation? Good Bad
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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
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What are the dangers of radiation?
small doses may burn tissue, disable cell division and the immune system.
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Small doses over time may cause cancer and genetic defects.
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Large doses Death from radiation sickness is often by dehydration because the digestive tract is damaged.
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Marie Curie Discovered radiation but eventually died from it.
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Turtles exposed to radiation
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What is the difference between nuclear reactions and chemical reactions?
Nuclear reactions involve changes in the nucleus. Chemical reactions involve valence (outer shell electrons.
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What is the difference between Energy produced in nuclear reactions and chemical reactions?
Nuclear Reactions produces much higher amounts of energy
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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
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What is the concentration at 200 years?
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How many years old is this when 20 % of the strontium is left?
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