Atomic Model History
Which scientist described atoms as tiny, solid spheres in the “billiard ball” model?
John Dalton
What property describes a material that can be hammered into thin sheets?
Malleability
A reaction starts with 25 g of reactants in a sealed container. What should the total mass of the products be, and which law explains this?
25 g. The law of conservation of mass.
What do we call the outermost occupied electron shell?
The valence shell.
What has hands but cannot clap?
A clock.
Which scientist discovered electrons and proposed the “plum pudding” or “raisin bun” model?
J. J. Thomson
An element has properties of both metals and non-metals. What type of element is it?
A metalloid
A neutral atom has an atomic number of 8. How many protons and electrons does it have?
8 protons and 8 electrons.
How many electrons fit in the first, second, and third shells?
First: 2. Second: 8. Third: 8.
What gets wetter the more it dries?
A towel.
Which scientist concluded that an atom is mostly empty space with a small, positively charged nucleus?
Ernest Rutherford
Name the four chemical families found in Groups 1, 2, 17, and 18.
Group 1: alkali metals, excluding hydrogen. Group 2: alkaline earth metals. Group 17: halogens. Group 18: noble gases.
An atom has a mass number of 23 and an atomic number of 11. How many neutrons does it have?
12 neutrons: 23 − 11 = 12.
A neutral nitrogen atom has 7 electrons. How are they arranged in its Bohr diagram, and how many are valence electrons?
2 in the first shell and 5 in the second shell. It has 5 valence electrons.
What belongs to you, but other people use it more than you do?
Your name.
Which scientist proposed that electrons occupy specific energy levels or shells around the nucleus?
Niels Bohr
Which family contains very reactive non-metals that tend to gain one electron when forming compounds?
Halogens
A neutral chlorine atom has an atomic number of 17 and a mass number of 35. Find its protons, neutrons, and electrons.
17 protons, 18 neutrons, and 17 electrons.
Draw a Bohr diagram for a neutral magnesium atom with atomic number 12 and mass number 24. Include the protons and neutrons.
Nucleus: 12 protons and 12 neutrons. Electron arrangement: 2–8–2.
What can travel around the world while staying in the same corner?
A postage stamp.
Put these atomic models in order from earliest to most recent: electron cloud, Bohr shell, plum pudding, billiard ball, Rutherford nuclear model.
Billiard ball → plum pudding → Rutherford nuclear model → Bohr shell → electron cloud.
Between lithium and potassium, which is more reactive? Between sodium and magnesium, which is generally more reactive? Explain both choices.
Potassium: alkali-metal reactivity increases down the group. Sodium: alkali metals are generally more reactive than alkaline earth metals.
A neutral atom has 12 electrons and 13 neutrons. Identify the element and give its atomic number and mass number.
Magnesium. Atomic number: 12. Mass number: 25.
An atom has an electron arrangement of 2–8–8. Identify the element, its period, and its chemical family. Explain why it is stable.
Argon. Period 3. Noble gases, Group 18. Its valence shell is full.
You see a boat full of people, but there isn’t a single person on board. How is that possible?
Everyone on board is married.