1.2 Flashcards
(9 cards)
What determines the size of the atom?
The volume of the electron orbits.
Do electrons have mass?
Electrons have virtually no mass.
Why are atoms neutral?
Because they have the same number of protons (positive) and electrons (negative), so their charges cancel out.
What happens to the number of electrons in an ion?
In an ion, the number of electrons is different from the number of protons.
What does it mean if an ion has a 2– charge?
It has two more electrons than protons.
What does the atomic number tell you?
The number of protons in an atom.
What does the mass number tell you?
The total number of protons and neutrons.
How do you calculate the number of neutrons?
Subtract the atomic number from the mass number.
n atom of gallium has atomic number 31 and mass number 70. How many electrons, protons, and neutrons does it have?
Protons = 31
Electrons = 31 (since it’s neutral)
Neutrons = 70 – 31 = 39
