Atomic structure and theory
A neutral atom always contains the same number of
protons and electrons.
The nucleus is the center of an atom. It consists of
protons and neutrons.
If carbon has an atomic number of 6, how many protons and neutrons are found in the carbon-14 atom?
6 protons and 8 neutrons
The atomic mass of silver (Ag) is 107, and the atomic number of silver is 47. How many neutrons does a neutral atom of silver contain?
60
In the electron cloud model, if you begin at the electron shell closest to the nucleus of an atom and move out, what is the number of electrons that each energy level or electron shell needs to fill the first four electron shells?
2, 8, 18, 32
If an atom has 3 electrons outside of its nucleus, which combination of protons and neutrons would result in a neutral atom?
3 protons, 3 neutrons
An isotope of an unknown element has 17 neutrons and a mass number of 32. What is the symbol of this isotope?
32/15P
The nucleus of an atom contains positively charged particles, called protons, and neutral particles, called neutrons. How is the nucleus of an atom held together?
A strong force exists between the particles in a nucleus, and this force is usually stronger than the electric forces that would pull them apart.
Democritus was a Greek philosopher living from c. 460 B.C. to c. 370 B.C. He wrote several suppositions on the properties of matter. Which of the following statements most closely describes Democritus's ideas about matter?
All matter is composed of tiny particles that can vary in shape, size, and weight.
According to Niels Bohr's atomic model, what occurs when an atom absorbs radiated energy?
An electron shifts from a lower energy level to a higher one.
Which of the following is true about the structure of an atom?
Electrons, neutrons, and protons are made up of even smaller constituents, such as quarks and gluons.
An atom is composed of a nucleus surrounded by electron clouds of varying sizes. The nucleus contains protons and neutrons, while electrons move about the nucleus in the electron clouds. Which of the following statements is also true of atoms?
Even though the nucleus of an atom is very small, it contains most of the atom's mass.
In the early 1880s, the British Scientist John Dalton worked to find the atomic mass of several common elements. How could knowing the atomic mass of an element help a chemist do his or her work?
The atomic mass could be used to identify an element.
Which of the following is true about the neutrons of an atom?
The neutrons do not affect how the atom interacts with other atoms, but they do have an effect on the mass and stability of the nucleus.
All matter, both living and nonliving, is made up of tiny particles called _______.
atoms
An atom is held together by
electric forces between the nucleus and the electrons.
A neutral atom could become a positively-charged particle through the loss of
electrons.
What is the name of the subatomic particles located farthest from the nucleus of the atom?
valence electrons
