Atomic Structure and the Periodic Table Flashcards
structure of an atom
contains a central nucleus that is made up of protons (positively changed) and neutrons (no charge). electrons (negatively charged) surround the nucleus in layers called shells
how are the shells arranged
the first shell, closest to the nucleus has 2 electrons. the rest of the shells can hold up to 8 electrons.
what determines the group (column)
the number of electrons in the outer shell
what determines the period (row)
the amount of shells
relative masses and charges
proton - 1m/u and +1
neutron - 1m/u and 0
electron - negligible and -1
what is the atomic number
proton number (total number of protons in the nucleus) in periodic table, it is the smaller number
what is the mass number
nucleon number (total amount of protons and neutron in nucleus) in periodic table, it is the largest number
group 8 (noble gases ) why not reactive
they have a full outer shell, therfore unreactive because they dont have to share electrons
what are isotopes
are different atoms of the same element that have the same number of protons but different number of neutrons (mass number changes but atomic stays the same)
why do isotopes have the same electronic configuration
because the electron number stays the same therefore chemical properties (reactivity) also stays the same as the proton number does not change
what atoms have equal numbers
protons and electrons
35 37
C C
17 17
abundances -
75.8% 24.2%
relative atomic mass = 35.5
(75.8x35)+ (24.2x37)
over
100
group 1 (alkali metals)
sodium, lithium, potassium (soft metal)
- density increases
- reactivity increases
- melting point decrease
when group 1 (alkali metals) react with water
react vigorously, hydrogen bubbles are produced
when group 1 (alkali metals) react with oxygen
they burst into flame
when group 1 (alkali metals) react with chloride
burst into flame, burn brightly
group 7 the halogens
chlorine, bromine, iodine (diatomic non-metals, poisonous, smelly)
-increase density
-decrease reactivity
halogens at room temp
fluorine =yellow gas
chlorine = pale green-yellow gas
bromine = red/brown liquid
iodine = grey solid, sublimes to purple
astatine = shiny black solid
ions
atoms that have gain or lost electrons therefore now have more or fewer electrons than protons
hallide
are halogens, when they react with other substances and become negative ions as they gain electrons
displacement reactions
where more reactive element displaces a less reactive element in its compound
sodium + iron chloride –> sodium chloride + iron
transition metals
high densities
high melting points
act as catalysts
form colored compounds
the noble gases
they are colorless, tasteless, odorless and monatomic as they go round as individual atoms
