Chemical elements Flashcards
Chemical Element
substance whose atoms all have the same number of protons
all of a particular element’s atoms have the same atomic number.
Chemical properties of elements
Density
Melting point
Boiling point
Molecule Types
Density
ratio of the mass of an object to its volume
physical property used to describe how tightly packed the molecules are in an object
d = M/V
commonly expressed in units of grams per cubic centimetre g/cm3 or g/ml
temperature goes down, the density usually becomes greater
Covalent compounds + boiling points
Acetone 56-57°C
Benzene 78-80°C
Chloroform 60-62°C
Ethyl alcohol 78°C
Carbon tetrachloride 76.7°C
Ionic Compounds + boiling points
Water 100°C
Nitric acid ~83°C
10% NaCl solution in water ~100.5°C
ionic compounds bp compared to covalent compounds bp
higher
due to the presence of ionic bonds in ionic compounds
boiling points of ethanol and methoxymethane
ethanol (with hydrogen bonding) 78.5°C
methoxymethane (without hydrogen
bonding) -24.8°C
branching in the molecule bp effect
van der Waals attractions less effective = lower
Na + O: observation, order of reactivity, product
Burns quickly with a bright yellow flame
1st - most reactive
Na2O, sodium peroxide - a yellow powder
Mg + O: observation, order of reactivity, product
Burns with a brilliant white flame
2nd.
MgO, magnesium oxide - a white ash.
Fe + O: observation, order of reactivity, product
Does not burn. Hot metal glows in oxygen and gives off yellow sparks.
3rd.
Fe203, iron oxide - an orange powder.
Cu + O: observation, order of reactivity, product
Does not burn. Metal eventually coats with a black layer.
4th - least reactive.
CuO, copper oxide - a black powder
K + H2O: observation, order of reactivity, product
Violent reaction with cold water. Floats and catches fire.
1st - most reactive.
Potassium hydroxide, KOH and hydrogen gas.
Na + H2O: observation, order of reactivity, product
Very vigorous reaction with cold water. Floats. Can be lit with a lighted splint.
2nd.
Sodium hydroxide, NaOH and hydrogen gas.
Ca + H2O: observation, order of reactivity, product
Less vigorous with cold water. 3rd.
Calcium hydroxide, Ca(OH)2 and hydrogen gas.
Mg + H2O: observation, order of reactivity, product
Very slow with cold water, but vigorous with steam.
4th.
Magnesium oxide, MgO and hydrogen gas.
Zn + H2O: observation, order of reactivity, product
Quite slow with steam.
5th.
Zinc oxide, ZnO and hydrogen gas
Fe + H2O: observation, order of reactivity, product
Slow with steam.
6th.
Iron oxide, Fe203 and hydrogen gas.
Cu + H2O: observation, order of reactivity, product
No reaction with steam.
7th - least reactive.
Mg + HCl: observation, order of reactivity, product
Vigorously reacts with a stream of gas evolving.
1st - most reactive.
Magnesium chloride, MgCl2 and hydrogen gas.
Zn + HCl: observation, order of reactivity, product
Quite slow reaction with a steady stream of gas evolving.
2nd.
Zinc chloride, ZnCl2 and hydrogen gas.
Fe + HCl: observation, order of reactivity, product
Slow reaction with a gentle stream of gas evolving.
3rd.
Iron chloride, FeCl2 and hydrogen gas.
Pb + HCl: observation, order of reactivity, product
Very slow and acid must be concentrated.
4th.
Lead chloride, PbCl2 and hydrogen gas.
Cu + HCl: observation, order of reactivity, product
No reaction.
5th - least reactive.
metals + hydrogen
metal hydrides
Hydrogen gas is passed over heated sodium, then sodium hydride is formed.
Acids and bases react with most metals to form
salt and hydrogen gas
more active than acid or base can undergo a single displacement reaction
What Causes Acid Rain?
non-metallic oxides - sulfur dioxide (SO2) and
nitrogen oxides (NOX) are emitted into the atmosphere and transported by wind and air currents.
SO2 and NOX react with water, oxygen and other chemicals to form sulfuric and nitric acids.
These then mix with water and other materials before falling to the ground.
While a small portion of the SO2 and NOX that cause acid rain is from natural sources such as volcanoes, most of it comes from the burning of fossil fuels.
Chemical properties of non-metal
- Non metallic oxides are acidic in nature.
- They do not dissolve in dilute mineral acids.
- They form stable compounds with hydrogen.
- Their chlorides are completely hydrolyzed by water.
non-metals with oxygen
form acidic oxides or neutral oxides
non-metals with water
do not react with water (steam) to evolve hydrogen gas
non-metal with acids
do not react with acids because they are negatively charged electrons.
non-metal with salt solution
do not react with salt solution but displace less reactive non-metal from the salt
non-metal with chlorine
form covalent chlorides which are non - electrolytes
A Binary Compound
formed from two types of elements
Metal + Metal = Metallic Compound
Metal + Non-Metal = Ionic compound
Non-Metal + Non-Metal = Covalent compound
