Topic 1 - Key Concepts in Chemistry Flashcards
Define compound
Two or more elements chemically bonded
Define element
Substance made up of only one type of atom
Mass of a proton
1 AMU
Mass of a neutron
1 AMU
Mass of an electron
Almost 0, 1/2000 AMU
Define mass number
Number of protons + neutrons
Define atomic number
Number of protons (in the nucleus)
Charge of a proton
+1
Charge of a neutron
0
Charge of an electron
-1
Define a molecule
Two or more atoms bonded together
John Newlands and Mendeleev arranged their periodic table in order of…
atomic mass
The modern periodic table is arranged in order of…
atomic number (proton number)
Explain why Mendeleev left gaps in his periodic table
to make the pattern fit for undiscovered elements
Explain why potassium and sodium are in the same group of the periodic table
They both have one electron in their outer shellThey react similarly
Explain why chlorine and bromine are group 7 of the periodic table
Both have 7 electrons in their outer shell
Explain why chlorine’s relative atomic mass is 35.5
Relative atomic mass is an average mass
Chlorine exists as Cl- 35 and Cl-37
75% is Cl-35 and 25% is Cl-37
(35 x 75 ÷ 100) + (37 x 25 ÷ 100) = 35.5
Explain why Mendeleev swapped Tellurium and Iodine’s position in his periodic table.
- Iodine has similar properties to other group 7 elements
- Iodine had similar chemical reactions to other group 7 elements
- Iodine is also diatomic
What subatomic particle did James Chadwick discover?
Neutron
How did Mendeleev’s periodic table become accepted by scientists?
They discovered the elements he’d left gaps forand they had similar properties to those he’d precited
Name two differences between Dalton and Rutherford’s model of the atom
Dalton said the atom was solid whereas Rutherford believed the atom was made of mostly empty space
Dalton believed that atoms were indestructible whereas the modern model of the atom is made of protons, neutrons and electrons
Name particle A
Electron
Which particle would be the electron. Explain your answer.
A
as it has the smallest mass so is deflected the most
or
it has is negative and attracted to the positive plate
Name particle B
Neutron/Proton
Name particle C
Neutron/Proton
Which particle would be the proton. Explain your answer.
C
as it has the largest mass so is deflected the least
or
it has is positive and attracted to the negative plate
Which particle would be the neutron. Explain your answer.
B
It has no charge so isn’t deflected by the magnetic field
i) 90
ii) 222
What is an isotope?
Atoms of the same element with the same number of protons and different numbers of neutrons
Which scientist discovered the neutron?
James Chadwick
Lithium’s relative atomic mass is 6.94. Is the Lithium-6 or Lithium-7 isotope more abundant? Explain your answer.
Lithium-7 as 6.94 is closer to 7
Compare the structures of lithium-6 and lithium-7 by referring to their subatomic particles
They both have the same number of protons (3)
They both have the same number of electrons (3)
They both have different numbers of neutrons (4)
or Lithium-7 has one more neutron
What group of the periodic table would this atom be found in?
1 (it has one electron in its outer shell)
What period of the periodic table would this atom be found in?
3 (it has three energy levels)
Explain, in terms of electrons, why magnesium and calcium are both in the same group of the periodic table.
They both have two electrons in their outer shell
What does the group number tell you about an element’s electron configuration?
The number of electrons in its outer shell
What does the period number tell you about an element’s electron configuration?
The number of energy levels
Draw the electron configuration of sodium
2,8,1
What is the proton number (Z) of this atom?
11 (same as the number of electrons)
