Chapter 4 Flashcards
The nucleus of an atom is positively charged (T/F)
True
The Rutherford model of the atom states that an atom consists of a nucleus and empty space outside the nucleus (T/F)
True
The mass of the proton is two times greater than that of the neutron (T/F)
False
A neutral atom that contains 11 protons also contains 11 neutrons (T/F)
True
When electrons gain additional energy, they move farther away from the nucleus (T/F)
True
Neutrons contribute to an atom’s atomic number, but not to its mass number (T/F)
False
The chemical properties of an element depend on the number and arrangement of the protons in the atoms (T/F)
True
Isotopes have different atomic numbers, but the same mass number (T/F)
False
Aristotle stated the four elements were earth, air, water, and fire (T/F)
True
The nucleus makes up about 99.9% of the mass of the atom (T/F)
True
The smallest piece of matter was named “atom” by…
Democritus
When an electron moves to a higher energy level, it ____ energy.
Gains
The electron was discovered by…
Thomson
Rutherford’s experiment demonstrated that…
atoms have a positively charged nucleus
In Rutherford’s experiment, most positive particles fired at the gold foil…
passed right through the foil
As a result of his experiment, Rutherford proposed that an atom has a ___, _____ charged nucleus
dense, positively
Bohr’s atomic model placed the electrons
in definite orbits around the nucleus
According to Thomson’s atomic model, atoms consist of…
negatively charged electrons scattered among positive charges
Almost all of the mass of an atom is found…
in the nucleus
The nucleus of an atom contains…
protons and neutrons
An electron has far less mass than…
a proton or a neutron
Atoms of the same element may differ in their numbers of…
neutrons
Mass number equals…
protons + neutrons
Atomic number equals…
number of protons
