atoms and molecules Flashcards
what are atoms
the smallest particle of an element
what is an atom made of
- neutrons
- protons
- electrons
properties of a proton (where is it in the atom etc.)
- inside the nucleus
- relative charge: positive
- relative mass: 1
properties of a neutron (where is it in the atom etc.)
- inside the nucleus
- relative charge: neutral
- relative mass: 1
properties of a electron (where is it in the atom etc.)
- around the nucleus
- relative charge: negative
- relative mass: negligible
how do you know when the atom is neutrally charged
when the number of protons and electrons are the same
how is the periodic table arranged
by the number of protons the element has
what is the other term for proton number
atomic number
what is the mass number of an atom
number of protons + number of neutrons in one atom
what is an isotope
atoms of the same element that have different number of neutrons (different mass number)
on the periodic table, the mass number below the element is in decimal places, how do you find the mass number of the atom then.
round up or down
e.g. boron: mass number on periodic table is 10.811. to find the mass number is to round up. 10.811~~11
how to find number of neutrons in an atom
mass number - proton number
how to find the number of electrons
- protons
- equals
- electrons
- proton number = number of electrons
what information can you obtain from the periodic table
- Number of protons (atomic number) of an element
- Number of electrons (same as the number of protons) in an electrically neutral atom of an element
- The mass number (when we round up or round down the relative atomic mass) of an element
what is chemical formula used for
to tell us how many elements are in a compound
what is a molecule
A molecule is a group of two or more atoms chemically combined together
what is diatomic moleules
- Molecules made of two atoms
- The individual molecules are represented in a certain way
when drawing the molecules of a compound, how do you know which atom is bigger
the atom with a bigger mass number
what is a valence shell
the outer most shell of the atom
what is the max number of electrons in each shell
1st shell: 2
2nd shell: 8
3rd shell: 8
4th shell: 32 (fyi)
what is an ion
atoms that have a different number of electrons than protons
how are ions formed
Ions are formed when atoms gain or lose electrons
what charge does ions have
Ions have either a positive or negative electrical charge
when an ion has less protons than electrons, what charge is the ion
negatively charged
