Science Study Guide: Atomic Structure
How is the number of neutrons calculated?
# of neutrons=Atomic mass-Atomic number
The number of protons in an atom with an atomic number of 18 is?
18 protons.
How many protons does potassium contain?
19 protons.
How many electrons can a K shell contain?
2 electrons.
How many protons, neutrons, and electrons does Tungsten contain?
74 protons 74 electrons 110 neutrons
How many electrons can an M shell contain?
8 electrons.
What is a model?
A model is anything that represents the properties of another object or system. Some models are miniature copies of the thing they represent, while other models represent things that can-not be seen. The model has been changed many times by different scientists. As each new discover occurred it described the atom with better precision and understand.
What is an Ion, which particle is responsible for creating ions and how do you calculate the charge of an ion?
A variation of an atom with more or less electrons than protons, which has a specific positive or negative charge.The electron is responsible for creating atoms.Add the number of electrons and the number of protons to get the charge of the ion.
What is an ion? What subatomic particle is responsible for creating an ion? Why could it only be that particle?
An ion is when an atom gains or loses electrons and now the atom has a charge instead of being neutral. Electrons are the subatomic particle responsible for creating an ion. It could only be electrons because changing the amount of protons would change the element and changing the amount of neutrons would not matter because they already have a neutral charge.
The name Democritus gave to the smallest possible particle of matter is the?
Atom
Define atomic mass and mass number.
Atomic mass-The mass of an atom. The unit used is AMU. Mass Number-The sum of the protons and neutrons in its nucleus.
What is an isotope?
Atoms of the same element that have the same number of protons but different numbers of neutrons.
How was the term "atom" derived?
Democritus thought the atom was the smallest piece of matter that "could not be cut." Therefore, he called it "atomos" which means "indivisible" or "not to be cut" in Greek.
What four forces govern the behavior of subatomic particles?
Electromagnetic force, strong force, weak force, and gravity.
What is the name of the force that describes the ability of an electron to be attracted to the proton due to opposite charges?
Electromagnetic force.
Describe the four forces and explain their role in the structure of the atom.
Electromagnetic force:keeps the electrons in orbit around the nucleus. Gravity:Gravity is the weakest force and the role of gravity on an atom is not quite understood. Strong force:Glues the protons together to form the nucleus. Without the strong force there would be no atoms. Weak force:Responsible for radioactive decay of the atom (the breakdown of the atom). The sun is powered by the weak force.
The scientist J.J. Thompson discovered the?
Electron
The arrangement and location of what subatomic particles determine the chemical properties of an atom?
Electrons
Which is the weakest force in the atom?
Gravity.
Which electron has more energy one in the L or N shell?
In the N shell.
What type of evidence is often used to discover information of things we can not see?
Indirect evidence.
How does the electromagnetic force differ from the other three forces?
It can either repel or attract particles.
Which particle is responsible for the different masses of atoms of the same element and why?
Neutrons change the mass of the atom because changing the proton would change the element and electrons are considered massless so they would not change the weight. Therefore the neutron is the only one with the ability to only change the weight of the atom.
How does the wave model of electron placement differ from the model of electron position proposed by Niels Bohr?
Niels Bohr's model explained where the electrons were in the atom. According to his model, electrons move in definite orbits around the nucleus, much like planets circling the sun. These orbits are located at specific distances from the nucleus. The orbits have only certain allowed energies, called energy levels. The wave model explained the more complex atoms. According to the wave model, electrons do not move about an atom in a definite path like planets around the sun. In fact, it is impossible to determine the exact location of an electron. Scientists can only predict where an electrons is most likely to be found. The location of an electron is based on how much energy it has. This is the model that we use today and it states that an atom has a small positively charged nucleus surrounded by a large area where there are enough electrons to make the atom neutral.
The small, heavy center of the atom is the?
Nucleus.
Define atomic number?
Number of protons in the nucleus of an atom.
Classify the three main subatomic particles according to location, charge, and mass.
Protons Mass=1.0073 AMU Charge=Positive Location=Nucleus Neutrons Mass=1.0087 Charge=Neutral Location=Nucleus Electrons Mass=0.00055 Charge=Negative Location=Electron cloud
The nucleus of an atom contains?
Protons and neutrons
The nucleus of an atom contains_____
Protons and neutrons.
Name the 3 subatomic particles.
Protons, neutrons, and electrons.
What is the mass of each of the 3 subatomic particles?
Protons-1 AMU Neutrons-1 AMU Electrons-1/1536 AMU
What is the charge of each of the 3 subatomic particles?
Protons-Positive charge Neutrons-No charge Electrons-Negative charge
Which subatomic particle was Bohr interested in finding?
Protons.
Draw the Bohr model for the atom 11Na26 That has a charge of +1
Protons:11 Neutrons:15 Electrons:10
How many protons, neutrons, and electrons does 61Co27 contain? Draw the Bohr model
Protons:27 Neutrons:34 Electrons:27
How many protons, neutrons, and electrons does nitrogen-15 contain? Draw the Bohr Model
Protons:7 Neutrons:8 Electrons:7
All nucleus particles are thought to be made of a combination of three what?
Quarks
Why is indirect evidence important in studying the structure of the atom?
Since the atom is so incredibly small, we are not able to see it. We have to use indirect evidence to allow us to gain further knowledge of the atom.
Define electron cloud?
Space in which electrons are likely to be found.
Particles smaller than the atom are called?
Subatomic particles
What are the particles smaller than atoms called?
Subatomic particles.
What is the name that Democritus gave to the smallest possible particle of matter?
The atom.
How is it possible that the atomic masses on the periodic table can have decimals?
The atomic mass is an average of the sum of isotopes.
Define atomic mass and describe how it is calculated?
The atomic mass is the mass of the atom. The mass is due to the mass of all the protons plus all the neutrons.
What is the center of the atom called? How was it discovered?
The center of the atom is called the nucleus. It was discovered by Ernest Rutherford. He discovered this by firing a stream of tiny positively charged at a thin sheet of gold foil. Most of the bullets passed straight through the sheet which showed him the atoms were mostly empty space. Some of the bullets however, bounced straight back because a positive charge repels a negative charge which was how he realized the an atom has a small, dense, positively charged center that he called the nucleus.
What is the charge of an atom?
The charge of the atom is neutral.
Which of the following forces within the atom is responsible for keeping electrons in orbit around the nucleus?
The electromagnetic force
Which two forces are responsible for holding the atom together?
The electromagnetic force and the strong force.
Name 4 names for the location of highest probability of finding an electron.
The electron cloud, the shell, the principal energy level, and orbital.
Describe the arrangement of electrons in an atom. Why is electron arrangement so important?
The electrons are arranged by the amount of energy that they have. The more energy that they have, the farther away they will be from the nucleus. Why is the arrangement so important?
What is meant when an atom is in the ground state? Excited state?
The ground state is when shells are filled with electrons to their maximum capacity before they start filling up the higher levels. The excited state is when electrons start jumping to the higher levels before they fill the lower shells to their maximum capacity.
How has the model of the atom changed over time?
The model changes as scientist discover new information.
Why is 99% of the mass of an atom inside the nucleus?
The nucleus accounts for 99% of the mass of an atom because the protons and neutrons are in the nucleus. Electrons are so tiny and since protons and neutrons have much more mass than electrons, the nucleus would account for most of the atom.
What is the small, heavy center of an atom called?
The nucleus.
How is the number of electrons calculated?
The number of electrons is equal to the number of protons. Which is also equal to the atomic number.
Nitrogen-14 and nitrogen-15 are isotopes of the element nitrogen. Describe how atoms of these isotopes differ from each other.
The number of protons will remain the same because the number of protons identifies the substance. If the number of protons change than it would not be the same element anymore. However, the number of neutrons will change. In this example, the 14 and 15 are the mass number. The number of neutrons in Nitrogen-14 is 7 neutrons. In Nitrogen 15 the number of neutrons is 8 neutrons.
Which principal energy levels can hold a maximum of 8 electrons?
The second principal energy level. Shell L.
Which is the strongest force in an atom?
The strong force.
What atom particle did J.J. Thomson discover?
Thompson discover "corpuscles". Today these particles are known as electrons.
How does glow in the dark work?
When electrons in the excited state drop back down to the ground state they have to release energy. The energy will create light which is the glow in the dark.