atoms and molecules Flashcards
(50 cards)
what did the indian philosopher Pakudha Katyayama state ?
particles normally exist in combined form which gives us various forms of matter
state the law of conservation of mass
The law of conservation of mass states that mass can neither be created nor destroyed during a chemical reaction.
what is the ratio of mass of hydrogen to mass of oxygen in water ?
1 : 8
what is the ratio of mass of nitrogen to mass of hydrofeb us ammonia?
14 : 3
state the law of constant proportions. who was it stated by?
The law of constant proportions was stated by Proust as “ in a chemical substance the elements are always present in definite proportions by mass.”
what are atoms?
atoms are the building blocks of all matter.
what is the unit of atomic radius ?
nanometers
what is the radius of a hydrogen atom?
10 to the power minus 10 m
what is the radius of a water molecule?
10 to the pwoer of minus 9 m
what is the radius of a haemoglobin molecule?
10 to the power minus 8 m
who was the scientist that suggested that symbols of elements be made from one or two letters of that element ?
Berzilius
what is IUPAC?
International Union of Pure and Applied Chemistry is an international scientific organisation which approves names of elements, symbols and units.
name some elements whose symbols are taken from their latin names.
Ferrum ( iron) , natrium ( sodium), and kalium (potassium).
learn table 3.1 on pg 34
finished learning
What did Dalton’s atomic theory state about mass?
According to Dalton, each element had a characteristic atomic mass.
Determining the mass of an individual atom is a difficult task. How did scientists determine relative atomic masses of elements?
using laws of chemical combination and the compounds formed.
what is atomic mass unit as per IUPAC recommendations?
‘u’ or unified mass
What is the standard reference for measuring atomic masses?
carbon - 12 isotope
what is one atomic mass unit?
one atomic mass unit is a mass unit equal to exactly 1/12th the mass of one atom of carbon - 12.
what is the relative atomic mass of an atom of an element?
it is defined as the average mass of the atom as compared to 1/12th the mass of one carbon -12 atom.
what are the atomic masses of hydrogen carbon oxygen respectively?
1, 12, 16
what are the atomic masses of nitrogen, sodium, magnesium and sulphur respectively?
14, 23, 24 , 32
what are the atomic masses of chlorine and calcium respectively?
35.5 u, 40 u
define molecule.
a molecule can be defined as the smallest particle of an element or a compound that is capable of an independent existence and shows all the properties of that substance.
