chapter 2 part 2 Flashcards
Early chemists used symbols of the Sun and planets to represent the _____ _______ _____ known at the time.
seven metallic elements
he definition of element that we use today was developed in the late ____
1700s
By the early ____ more than
__ elements had been identified, including ______, ______, _____. As the science of chemistry developed, more and more elements were identified.
1800s, 30, oxygen lead and mercury
To help in the study of _____ and _____, chemists tried to group elements according to their ______.
elements,elements,properties
But this became confusing because different scientists organized elements in ______. A new organization was needed so that everyone would be using the same system.
different ways
One of the first attempts by a scientist to create a better system for organizing the elements was made by _____ _______, an English chemist
John Dalton
In the early ____, John dalton developed a new set of symbols for elements.
1800s
Dalton’s symbols were later modified by Swedish chemist ____ ______ _______
Jöns Jacob Berzelius.
In ____, Berzelius suggested using rather than pictures to represent each element. The first letter (capitalized) of an element would become the symbol.
1814, letters,
For elements with the same _____, such as hydrogen and helium, a small second letter would be added.
first letter
It was soon realized that the elements could be listed in order of increasing ____ _____
atomic mass.
what is atomic mass
Atomic mass is the mass of one atom of an element.
How were scientists were able to determine the average mass of an atom of other elements
by comparing it with the mass of a carbon atom (which is 12.0).
did scientists accpet the “law of octaves,”
no
who made the law of octaves
John Newlands
what is the law of octaves
John Newlands recognized a pattern when elements were listed by increasing atomic mass. He noticed that properties of elements seemed to repeat through this list at regular intervals.
Russian chemist _____ _______ was able to organize the elements in a way that reflected the patterns in the properties of the elements.
Dmitri Mendeleev
what were some of the 63 elements mendeleev collected at his time (mid 1800s)
lithium, carbon, nitrogen, oxygen, fluorine, sodium, silicon, phosphorus, sulfur, and chlorine.
He then wrote down the properties of each element on a card, such as He then wrote down the properties of each element on a card, such as ______ _____ _____ _____. Using these cards, he tried to sort the elements into a pattern based on their properties.
.
melting point, density, and colour.
He also wanted to find a pattern that would allow him to _____ the properties of elements NOT yet discovered.
predict
why is todays new elements that are being discovered NOT stable.
They have been created in laboratories with special equipment and have never been found in nature. Still, no matter how the elements are identified, they all have their place in the periodic table.
Notice that the periodic table is a series of ____ , ____ and _____.
boxes , rows and coulumns
Each horizontal row is called a ____ (numbered from _ to _).
period,1 to 7
each vertical column forms a ____, or ____, of elements (numbered from _ to __).
group, or family,1 to 18
