elements and atomic structure Flashcards
what are elements?
substances that contain only one type of atom
what do atoms of one electron have?
the same number of protons and electrons
where are electrons shown?
in the periodic table
what are atoms composed of?
electrons surround a nucleus consisting of protons and neutrons
what is the relative mass, relative charge and location of protons?
1, +1, in the nucleus
what is the relative mass, relative charge and location of neutrons?
1, 0, in the nucleus
what is the relative mass, relative charge and location of electrons?
1/2000, -1, around the nucleus
what is the atomic number?
the number of protons in an atom
how is the periodic table arranged?
in increasing order of atomic number
the mass number of an atom =
number of protons + number of neutrons
why are electrons important?
they are the bit of the electron that takes part in bonding
how many electrons does shell 1 hold?
2
how many electrons does shell 2+ hold?
8
how would chlorine (17 electrons) be written?
2, 8, 7
how do you know what group an atom is in from its electronic configuration?
from the number of atoms on the outermost shell e.g chlorine is in group 7
how do you know what period (row) an atom is in from its electronic configuration?
from the number of shells with electrons in them e.g chlorine is in period 3
what makes an atom stable
and what does this cause?
if its shells are all full
and that the noble gases in group 0 / 8 are nonreactive
what do elements do to have full outer shells?
they exist as diatomic molecules e.g. hydrogen (H2), oxygen, chlorine, bromine, iodine, nitrogen
