Chapter 10 - Atoms Flashcards
All matter consists of what?
Atoms
Where are protons and neutrons found?
In the nucleus
Where are electrons found?
Orbiting the nucleus in electron clouds
State the charge of each subatomic particle: Proton, Neutron, Electron
Proton: Positive (+)
Neutron: No charge (0)
Electron: Negative (-)
The atomic number is equal to the number of _____ in an atom
protons
In an element that has no overall charge, the atomic number also helps you identify what? Why?
The number of electrons; the number of protons (+) and electrons (-) must equal to create no overall charge in the element. So if the atomic number is 5 in an element (5 protons), then the element also has 5 electrons.
What is the mass number?
The sum of the numbers of protons and neutrons in the nucleus of an atom.
What is the atomic mass of an element?
The number that averages all of the masses of isotopes of an element together.
If O-10 takes up 50% of all Oxygen (O) atoms in nature and O-4 takes up 50% of all Oxygen (O) atoms in nature, than what is the atomic mass for oxygen?
10 * 50% = 5
4 * 50%. = 2
___________+__
7 atomic mass units (amu)
The number after the hyphen in an atom (H-12) is the atom’s what?
Mass number
How do you find the number of neutrons in an element?
Subtract the atomic number(# of protons) by the atomic number
Element:Atomic Mass :: Atom:_____
Mass number
What defines an element(no other element has the same ____)?
Its atomic number
Two atoms have the same atomic number but a different number of neutrons(and therefore a different mass number). What are theses elements called?
Isotopes
The electron is a lot (larger, smaller) than a proton or neutron
Smaller
If an atom has more protons than electrons, then it is what?
A positively charged ion
Describe gravitational force.
All objects attract each other. The larger the mass and the greater the distance between objects, the stronger the gravitational force.
Describe electromagnetic force.
Objects with alike charges repel and objects with different charges attract.
Describe strong force.
The close distance between the neutrons and protons in the nucleus of an atom causes strong force and keeps the nucleus together. Without the neutrons, there would be no buffer between the protons, causing them to repel each other.
Describe weak force.
In some unstable atoms, neutrons have the ability to change electromagnetic charges; it can turn into a proton or electron. Weak force plays a key role in radioactive elements
Who thought that you could keep cutting a particle infinitely?
Aristotle
Who thought that you would end up with a particle that couldn’t be divided?
Democritus
Who experimented with different substances and developed an atomic theory?
John Dalton
Who found that atoms could be divided into further parts and discovered the electron of the atom? He also created the plum-pudding model.
J.J. Thomson
Who used a gold-foil experiment to discover the small, dense nucleus of the atom?
Ernest Rutherford
Atoms consist mostly of _____
Empty space?
Who discovered that electrons can jump between certain paths, or energy levels?
Niels Bohr
What are electron clouds?
Regions around the nucleus where electrons are likely to be found.
Up to how many electrons can each energy level hold?
1st: 2
2nd: 8
3rd: 18
Is it possible to have 1 electron on the first energy level, and 4 on the 2nd? Why or why not?
No; the 1st energy level must reach its maximum capacity (2)before electrons can go on the 2nd energy level.
The outer energy level of an atom is called its _____ ,and the electrons on that outer shell are called_____.
Valence shell
Valence electrons
The Lewis structure has dots around the atom’s symbol. What do the dots represent?
Valence electrons
The Octet rule states what?
That the goal of atoms is to have 8 electrons on its valence shell. An atom is more likely to gain electrons from another atom if the number of valence electrons is closer to 8.
State Dalton’s atomic theory (3 statements)
- All substances are made of atoms, or small particles that cannot be created, divided, or destroyed.
- Atoms of the same element are exactly alike, and atoms of different elements are different.
- Atoms join with other atoms to make new substances
If an atom has 5 protons in its nucleus and 7 electrons, it is what?
A negatively charge ion
Describe the nucleus
Small, dense, and positively charged.
Which subatomic particle is the smallest, and therefore has the least amount of mass?
Electron
If an atom has the same amounts of protons and electrons, it is called a ______
Balanced atom
If an atom has a mass number of 10 and an atomic number of 5, then how many neutrons are in the nucleus of this atom?
5 ((10 protons + neutrons) - 5 protons = 5 neutrons)
What is an atom?
The smallest particle of an element that can’t be divided
Electrons are likely to be found where?
In the electron clouds
Who discovered the electron, which proved that atoms can be further divided into smaller parts?
J.J. Thompson
The discovery of the _____ proved that atoms can be further divided into smaller parts.
Electron
If an balanced element has an atomic number of 7, how many valence electrons are there?
1st shell - 2 2nd shell (Valence shell ) - 5
An atom with 15 electrons will have how many dots on its Lewis Structure?
1st shell: 2
2nd shell: 8
3rd shell (valence shell): 5
5 dots
