Periodic table is the representation of elements in an order
The history of periodic table can be summarized as
a) 1829 : Johann Dobereiner proposed the triad rule. According to him we can classify the elements in a triad where the atomic mass of middle element is average of atomic mass of the near by two atoms.
For example : Li, Na and K is a triad. Where atomic mass of Na is average of atomic mass of K
atomic mass of Na = 7+ 39 / 2 = 23
However, with the further discovery of elements the law was rejected.
b) 1864 : John Newland proposed the law of octave. According to him we can arrange the elements in a set of seven elements where the property of second set of seven elements will resemble the properties of first of seven elements or property will be repeated after seven elements. This was also rejected due to its limited applicability.
c) Meyer : He arranged some 28 elements into six different families based on their atomic masses. The members of each familiy shared some common properties.
d) 1869 : Mendleev : He actually developed a periodic table based on atomic mass of elements. He arranged the elements into groups and periods. He even left space for some undiscovered elements, which were later on discovered.
e) 1916 : Henry Moseley : He finally arranged elements based on their atomic number based on X-ray studies. He proposed the modern periodic law that the periodic properties of elements are due to atomic number of elements.
We find out the molar mass of NH₃.
atomic mass (N)=14 u
atomic mass (H)=1 u
atomic weight (NH₃)=14 u + 3(1u)=17 u
Therefore the molar mass of NH₃ will be: 17 g/mol
Then:
1 mol of water=18 g
2) We know that:
1 mol of any substance=6.022 * 10²³ particles.
3)We calculate the mass of 8.00 *10²² molecules
18 g of water----------------------------6.022*10²³ molecules
x---------------------------------------------8.00*10²² molecules
x=(18 g of water * 8.00*10²² molecules) / 6.022 * 10²³ molecules=2.39 g
Answer: the mass of 8.00 *10²² molecules of NH₃ would be 2.39 g.
Answer:
Copper, gold, silver, etc.
Explanation:
Most metals are ductile. Ductile just means that it can be hammered or stretched into wire without breaking; metals can do this and are great conductors of electric current
(4) Increase citizen participation in government
Primary: a way for citizens to vote for new government officials, not too influenced by party leaders
Secret Ballot: keeping a voter's votes private from others
Recall: a way for citizens to remove a government official from office
Referendum: a way for citizens to vote for or against something proposed by the legislature
During the Progressive Era, many local governments were lead by corrupt political machines. They would rig elections in their favor as well as threaten those who voted against them. Many would appoint their supporters who weren't usually qualified to government positions as incentive to vote for them (I don't know if you care but that's called the spoils system).
<span>It's not (1) because the whole point of primaries, secret ballots, recalls, and referendums was so political machines were not dominating
</span>It's not (2) because none of this has a lot to do with Native Americans
It's not (3) because the political machines were a <u>local</u> government problem, not federal
It <u><em></em>IS</u> (4) because by getting more people involved in the government, they can elect qualified officials, vote on laws that best benefit the people, and minimize corruption.
There is 3 electrons at the outer layer of the Al atom. So when the valence electrons were removed and Al ion at a stable status, the Al ion is +3 charge.