What distinguishes the atoms of one element from the atoms of another element?
number of protons
How do the isotopes of a given element differ from one another?
number of neutrons, mass number
What equation tells you how to calculate the number of neutrons in an atom?
number of neutrons = mass number - proton number
How is atomic number different from mass number?
atomic number = number of protons only, but mass number = number of protons and
number of neutrons added together
What does the number 18 represent in oxygen - 18?
mass number
What subatomic particle did Thomson discover?
Electron
Is the charge of the nucleus of every atom positive or negative? Explain.
positive; electrons are not found there so the charge comes only from the positively
charged protons
Which subatomic particle is located in the nucleus?
Proton
Why is an atom electrically neutral?
they contain equal number of protons and electrons
What does the atomic number of each atom represent?
Number of protons
What is the difference between the mass number and the atomic number of an atom?
mass number = proton number + neutron number
atomic number = proton number
Name two ways that isotopes of an element differ.
unequal number of neutrons unequal mass number
What data must you know about the isotopes of an element to calculate the atomic
mass of that element?
percent abundance, atomic mass of each isotope
If you know the atomic number and the mass number of an atom, how can you determine the number of protons, neutrons, and electrons of that atom?
proton number = atomic number
neutron number = mass number -proton number
electron number = proton number