chapt 8 : atoms and molecules Flashcards
(17 cards)
what does proton also mean?
number of electron and atomic number
what does relative atomic mass also mean
mass number and nucleuon number
what does proton + neutron =
relative atomic mass
how to find neutron
relative atomic mass - proton
how to find proton
p=e
relative atomic mass - neutron
are proton number unique?
yes
are relative atomic mass number unique ?
no
how many electron can the first shell hold?
2 electrons
how many electrons can the 2nd shell and the subsequent shells hold?
8 electrons
what is in the nucleus ?
protons and neutrons
what does it mean when an atom has maximum amount of valence electrons?
it means that the atom is very stable an unreactive, it has a stable electronic configuration
what are ions
ions are charged particles. they are formed when an atom loses or gains electrons
what is a positive ions
an atom is changed into a positive ion when it loses electrons.
metals, with 1,2,3 valence electrons tend to lose electrons to form stable noble gas configuration
what is negative ion
an atom is changed into a negative ion when it gains electrons.
non-metals, with 5,6,7 valence electrons tend to gain electrons to form stable noble gas configuration
electrons in the same period contains the same number of electron shells
SHELLS
elements in the same group contains the same number of valence electron
VALENCE ELECTRONS
what are molecules
molecules are formed when 2 or more atoms are chemically combined together
