Atomic Structure And Periodic Structure Flashcards
What are atoms
All the stuff elements and compounds are made of
What are the subatomic particles that make up a atom
Electron neutron and protons
What charge do electrons have
-1
What takes up the most volume in a atom
The orbitals
Where is most of the mass concentrated in the atom
The nucleus
Is the diameter of the nucleus big or small compared to the diameter of the atom
Small
What’s in the nucleus
Protons neutrons
What is the relative mass of the proton
1
What is the relative mass of the neutron
1
What is the relative mass of the electron
0.0005
What is relative charge of proton
+1
What is the relative charge of the neutron
0
What is the relative charge of a electron
-1
What is mass number
Total number of protons and neutrons in the nucleus
What is atomic mass
Number of protons in the nucleus
What is true about protons of an element
All atoms of the same element have the same number of protons
If a atom is neutral what is true about the protons and electrons
The are equal
How do you work out the number of neutrons
Mass number minus atomic number
What does a negative charge on atom mean
More electrons than protons
What does positive charge on atom mean
More protons than electrons
What are isotopes
Atoms of the same element with same number of protons but different number of neutrons
What decides the chemical properties of an element
The number and arrangement of electrons
why do isotopes of the same element have the same chemical properties have the same chemical properties
because they have the same arrangement and number of electrons which determines the chemical properties
why do isotopes of an element have different physical properties
because physical properties tend to depend on the mass of an atom
what do physical properties depend on
mass of the atoms that make it up
what is the relative atomic mass
weighted mean mass of an atom compared to 1/12th of the mass of an atom of carbon 12
what is the relative isotopic mass
mass of an isotope compared to 1/12th the mass of an atom of carbon 12
what is the relative molecular mass or relative formula mass
the average mass of a molecule or formula unit compare to 1/12th of the mass of an atom of carbon 12
how do you work out the relative molecular mass
add up the relative atomic mass values
what is relative molecular mass used for
simple molecules
what is relative formula mass used for
used for compounds that are ionic or giant covalent
how do you work out the relative formula mass
add the relative atomic masses of the ions or atoms
how to work out the relative atomic mass of an element from its isotopic abundance
step 1: multiply each relative isotopic mass by its % relative isotopic abundance and add up the results
step 2: divide by 100
where are mass spectra produced from
mass spectrometers
what are mass spectrometers used for
devices used to find out what samples are made up of by measuring the masses of their components
what can mass spectra tell us
relative isotopic masses and abundances of different elements
what is on the y axis and x axis on a mass spectra
abundance of ions on the y axis
and m/z values on the x axis
what is a m/z values
mass/charge ratio
what can you assume about the m/z value
charge of ions is +1 so we can assume x axis is the relative isotopic mass
how to work out relative atomic mass from a graph
step 1:multiply each relative isotopic mass by its relative isotopic abundance and add up the results
step 2:divide by the sum of the isotopic abundances
Silicon can exist in three isotopes. 92.23% of silicon is 28Si and 4.67% of silicon is 29Si. Given that the Ar of silicon is 28.1, calculate the abundance and isotopic mass of the third isotope.
100% – 92.23% – 4.67% = 3.10%
28.1 = ((28 × 92.23) + (29 × 4.67) + (X × 3.10)) ÷ 100
28.1 = (2717.87 + (X × 3.10)) ÷ 100
2810 – 2717.87 = X × 3.10
29.719 = X
So the isotopic mass of the third isotope is 30
Chlorine has two isotopes. 35Cl has an abundance of 75%
and 37Cl has an abundance of 25%. Predict the mass spectrum of Cl2.
step 1:
35Cl – 35Cl: 0.75 × 0.75= 0.5625
35Cl – 37Cl: 0.25 × 0.75= 0.1875
37Cl – 35Cl: 0.25 × 0.75= 0.1875
37Cl – 37Cl: 0.25 × 0.25= 0.0625
step 2: 0.1875 + 0.1875 = 0.375.
step 3:Divide all the relative abundances by the smallest relative abundance to get the smallest whole number ratio.
[(35Cl – 35Cl) (35 + 35 = 70) (0.5625 ÷ 0.0625 = 9)]
[(35Cl – 37Cl) (35 + 37 = 72) (0.375 ÷ 0.0625 = 6)]
[(37Cl – 37Cl) (37 + 37 = 74) (0.0625 ÷ 0.0625 = 1)]
what happens when molecules are bombarded with electrons in mass spectrometry
electron removed from molecule to form molecular ion m+
how do you molecular mass of a compound when looking at mass spectra
look at molecular ion peak
on a mass spectra which peak is the molecular ion peak
the one with the biggest m/z value
what do electrons move around the nucleus on
quantum shells/energy levels
what do shells contain
subshells
what do subshells contain
orbitals