Atomic Theory
This ancient Greek philosopher proposed that matter was made of tiny, indivisible particles called atomos.
Who was Democritus?
An atom of selenium has an atomic number of 34. Therefore, it contains this many protons.
What is 34
What is the area in the EM spectrum called that can be detected by the human eye?
What is visible light
This is the maximum number of electrons that can occupy the first principal energy level.
What is 2
This subatomic particle has a +1 charge and is found in the nucleus.
What is a proton
This scientist used a cathode ray tube and concluded that atoms contained negatively charged particles.
Who is JJ Thompson
Fluorine-19 has an atomic number of 9. How many neutrons does this isotope contain?
What is 10
Consider the neon lamp simulation. Of the colors in visible light, this color has the shortest wavelength and highest frequency.
What is violet
Electrons in an atom can only occupy certain specific energy levels (or absorb and release specific amounts of energy). This idea is described by the term ___.
What is quantized
An atom of chlorine has an atomic number of 17 and a mass number of 35. How many neutrons does it have?
What is 18
Thomson's discovery of the electron led to this atomic model, in which electrons were embedded within a positively charged substance.
What is the plum pudding model, or blueberry muffin or chocolate chip cookie.
An atom contains 12 protons, 10 electrons, and 12 neutrons. Identify the element and its charge.
What is Mg²⁺, or magnesium with a +2 charge?
As the wavelength of electromagnetic radiation increases, the frequency does this.
What is decrease
When an electron absorbs energy, it can move from its ground state to a higher energy level. This higher-energy condition is called this.
What is excited state
Using the whiteboard or piece of paper draw the Bohr model for potassium (K), which has an atomic number of 19.
What is 2 electrons in the first shell, 8 in the second, 8 in the third, and 1 in the fourth (2-8-8-1)?
In Rutherford's gold foil experiment, most alpha particles passed straight through the foil, but a small number were dramatically deflected. This evidence led him to conclude that atoms have this.
What is a small, dense, positively charged nucleus?
An atom has 17 protons and 18 electrons. Is it a cation or an anion, and what is its charge?
What is an anion with a −1 charge?
How would you describe the relationship between wavelength & frequency.
What is they are inverses of one another. As one increases the other decreases and visa versa
Explain why each element produces a unique bright-line emission spectrum.
Each element has unique, quantized electron energy levels. When electrons fall between specific levels, they emit photons with specific energies/wavelengths, producing a unique pattern of spectral lines.
Lithium has two naturally occurring isotopes: Li-6 (7.5%) and Li-7 (92.5%). Calculate its average atomic mass.
What is approximately 6.93 amu?
Put these atomic models in chronological order: Rutherford model, Democritus's idea, Bohr model, Thomson's plum pudding model, modern electron cloud model.
What is Democritus → Thomson → Rutherford → Bohr → modern electron cloud model?
Three isotopes of an element have masses of 24 amu (79%), 25 amu (10%), and 26 amu (11%). Calculate the element's average atomic mass.
What is 24.32 amu?
Two electromagnetic waves are traveling at the same speed. Wave A has a wavelength of 400 nm, while Wave B has a wavelength of 800 nm. Which has the greater frequency and therefore greater energy?
What is Wave A, the 400-nm wave?
An electron absorbs a photon and moves from energy level 2 to energy level 5. What happened to the electron's energy, and what will happen when it returns to a lower energy level?
What is the electron gained energy and became excited; when it falls to a lower energy level, it releases energy as a photon of light?
An element has an average atomic mass of approximately 10.81 amu. Its naturally occurring isotopes are B-10 and B-11. Which isotope must be more abundant, and how can you tell?
What is B-11? The average atomic mass is much closer to 11 than to 10, so B-11 must be more abundant.