Ch 3 Atoms and Elements Flashcards
what is an atom
an atom is a particle of matter that cannot be broken down further by chemical means
what is an element
an element only contains one type of atom
what would you see inside an atom
mostly empty space with a tiny nucleus at the centre and a cloud of electrons orbiting at a high speed at (a) (dif specific) distance(s)
what group are the metals on the periodic table
Group I or II
what group are the non-metals on the periodic table
Group 0 or IV
short form describing an element
proton number at the top, nucleon number at the bottom, element on the side
what are isotopes
atoms of the same element with the same proton number but a different neutron number
name three isotopes of carbon
carbon-12, carbon-13, carbon-14
what is a radioisotope
give 2 examples
radioactive isotope
isotope of an element with an unstable nucleus that will decay and emit radiation
eg. cobalt-60, carbon-14, uranium-235
how do you use radioisotopes to check for leaks
Mix radioactive material with the fluid inside the pipe, radiation cannot be detected through the pipe but it can be detected where it leaks out with a Geiger counter
name some uses of radioisotopes
Check for leaks
Treat cancer
Kill germans and bacteria
why are spices often treated with radiation, name 2 radioisotopes used for this
to kill germs or micro-organisms that cause decay
cobalt-60 and caesium-137
why can radiation kill us
it can kill cells, damage organs, cause cancer, radiation sickness
why is radiation used for cancer
it kills cancer cells more readily than it kills healthy cells
what does the period number tell you
the number of shells there are
what does the group number tell you
the number of valency electrons there are
isotopes of the same element have the same number of _____ ______
meaning that their _____ are the same
valency electrons
chemical reactions are the same
If the outer shell is full ….?
outer shell has a stable arrangement so the atom will be unreactive
name the metals and non metals in the first 20 elements
metals: (Lithium) Li , (Beryllium) Be, (Sodium) Na, (Magnesium) Mg, (Aluminium) Al, (Potassium) K, (Calcium) Ca (7) (Li Be Na Mg Al K Ca)
non-metals: H, He, B, C, N, O, F, Ne, P, S, Cl, Ar (12)
metalloids: B, Si
define conductor
a substance that allows heat and electricity to pass through it easily
define brittle
breaks up easily when struck
define ductile
can be easily be drawn out into a wire
define sonorous
makes a ringing noise when struck
define density
mass per unit of volume
define malleable
can be bent/hammered into shape
why is aluminium used for outdoor electricity cables
good conductor light most abundant metal quite strong light forms protective layer so won't rust away
three main general properties that distinguish metals from non-metal
metals form positive ions when they react (eg. Na+) with the exception for a non-metal being H+
conduct electricity
hard and strong
high melting points
physical properties of non-metals
doesnt conduct electricity or heat lower melting and boiling points- many are gases at rpo temperature brittle not malleable or ductile dull in solid state solid non-metals have low density
chemical properties of non-metals
often form negative ions when they react eg O 2-
React with oxygen to form ACIDIC OXIDES
aqueous solutions will turn litmus RED
chemical properties of metals
form positive ions when they react (eg. Na+)
react with oxygen to form oxides that are BASES
oxides can NEUTRALISE ACIDS
name some metals that have a low density
aluminium
sodium
lithium
potassium
explain how the chemical properties of metals and non-metals can be used to tell them apart
metals from BASIC OXIDES
non-metals form ACIDIC OXIDES
