Physical Science: Chapter 14

What is the charge on a proton?

+1e

The mass of an electron is about __.

1,800 times heavier than a proton

What is the fundamental property of matter that can either be positive or negative?

Charge

A particle found in the nucleus with mass similar to the proton but with zero electric charge

Neutron

What particle in an atom has no electric charge?

Neutrons

Many models have been developed to explain the nature of atoms. The model that helped scientists to understand energy levels of atoms was developed by __.

Niels Bohr

Who is Niels Bohr and what did he discover?

Niels Bohr is a Danish physicist who proposed the concepts of energy levels. He built a model in which the electrons must be in a specific energy level.

What model helps scientist understand energy levels?

Niels Bohr's model

How much larger is a proton compared to an electron?

1,836

How much larger is a neutron compared to an electron?

1,839

How many electrons can fit in the fourth energy level?

18

Two of the energy levels can hold eight electrons each. Which energy levels are they?

2 and 3

Make a true statement regarding electric charge.

A positive charge attracts a negative charge and repels other positive charges.

What is the atomic number?

Amount of protons

The number of protons in the nucleus of an atom; determines what element the atom represents.

Atomic number

Is electric charge a property of just electricity or is charge a property of all atoms?

Electric charge is a property of all atoms.

One of two forces that hold atoms together is called __.

Electric force

A fundamental property of matter that can be either positive or negative

Electrical charge

Protons and neutrons are held together by what?

Electromagnetic force

A particle with an electric charge (-e) found inside of atoms but outside the nucleus

Electron

An atom contains __ in various energy levels.

Electrons

The electric charge on an atom is neutral because the number of protons is the same as the number of __, and each of their individual charges cancels out.

Electrons

Which particle occupies the space outside the nucleus, in a "cloud?"

Electrons

The smallest unit of electric charge that is possible in ordinary matter; represented by the lowercase e.

Elementary charge

Who is Ernest Rutherford and what was his experiment about?

Ernest Rutherford found a tiny, dense core at the center of an atom and called it the nucleus.

Atoms of the same element that have different numbers of neutrons in the nucleus

Isotopes

Atoms with the same atomic number but different atomic mass are called __.

Isotopes

__ are atoms of the same element with a different number of neutrons.

Isotopes

What does it mean when a nucleus is "stable?"

It stays together

Who is J.J. Thomson?

J. J. Thomson was an English physicist who discovered electrons.

A particle with a negative charge was discovered by English physicist, __, and is called the __.

J.J. Thomson; electron

The atoms number of protons plus the number of neutrons in the nucleus of an atom is known as the (atomic number, mass number).

Mass number

The number of protons plus the number of neutrons in the nucleus

Mass number

What are the building blocks of matter?

Molecules and atoms

Protons and neutrons are found grouped together in the __.

Nucleus

Several scientists, including Ernest Rutherford, preformed an experiment that helped improve the model of atom by realizing the inner core of the atom housed most of the mass. This core has a special name, the __.

Nucleus

The tiny core at the center of an atom containing most of the atom's mass and all of its positive charge

Nucleus

What do we call the tiny core at the center of the atom, containing most of the atom's mass and all of its positive charge?

Nucleus

A particle found in the nucleus with a positive charge exactly equal and opposite to the electron

Proton

How do you calculate the number of neutrons in an isotope? Ex: Carbon-14

Protons + Neutrons = Mass number Example on page 319

The two particles that make up most of the mass of the atom are called the __ and the __.

Protons and neutrons

What two particles mainly make up the mass of the nucleus?

Protons and neutrons

Atoms are made of three basic components. Name these three particles.

Protons, neutrons, and electrons

A nucleus is __ if it spontaneously breaks up, emitting particles or energy in the process

Radioactive

If a nucleus is unstable and breaks apart, it is called _.

Radioactive

Two negative charges will (attract, repel) one another.

Repel

Is a proton smaller or larger than a neutron? What is the difference in numbers?

Smaller; 3

A nucleus is __ if it stays together

Stable

What are the four forces inside atoms? Rank them strongest to weakest.

Strong nuclear force, electromagnetic force, weak force, gravity

Why don't all electrons in an atom fall to the lowest level?

The lowest level can only hold two electrons.

Radioactive means __.

The nucleus of an atom is unstable and will eventually change

The atoms number is __.

The number of protons in the nucleus

All atoms of the same elements have __.

The same number of neutrons in the nucleus

All atoms of the same element have __.

The same number of protons

Protons and neutrons in the nucleus are held together by __.

The strong nuclear force

What is the charge on an atom that is complete?

Zero