Chapter 2 Flashcards
Relative Mass, charge and location of neutron, proton and electron
Electron: negative, around nucleus in shells and negligible mass about 1/2000 mass of proton
Neutron: no charge, in nucleus and 1 relative mass
Proton: positive, in nucleus and 1 relative mass
However neutron has slightly higher mass than proton but virtually the same.
Why are there neutrons in the nucleus? Whats the purpose?
Why are there more neutrons than protons?
Neutrons provide the glue that hold the nucleus together despite the electrostatic repulsion between its positively charges protons as same charges repel.
This is why most atoms contain the same number or more neutrons than protons. Neutrons are especially important in large nuclei.
What defines an element (what makes an element unique to another element)?
What is the atomic number?
Number of protons
What is an isotope?
Element with same number of protons but different number of neutrons which means the nucleus size is different
Why do isotopes of same element react the same way (chemically)?
Chemical reactions involve electrons around the nucleus not the neutron number and as the number of electrons is the same it has no effect on reactions of an element
Are there different physical properties of same element isotopes?
If so explain and give examples
Higher mass nuclei of isotope with more neutrons there will have higher m.p/b.p, higher density as there is more mass in same volume
Some isotopes are more radioactive and less stable
What is an ion
Charged atom with different number of electrons as protons
Cation?
Positive ion
Anion?
Negative ion
Why cant the relative mass of an isotope be adding proton, neutron and electron together.
Hint: mass defect
Strong nuclear force holding together protons and neutrons comes at the expense of the loss of a fraction of their mass
The mass defect is the small amount of mass lost because of the strong nuclear force
How do we calculate the mass of atoms of some mass is lost to hold the nucleus together?
Standard isotope carbon 12 is used. This carbon mass is exactly 12 atomic mass units(12 u). It is based on 1/12th the mass of carbon 12.
1u is approx the mass of 1 proton.
What is relative isotopic mass?
Mass of an isotope relative to 1/12 mass of a carbon 12 atom
Relative isotopic mass has no units as it is a ratio of two masses
What is relative atomic mass
Weighted mean mass of atoms of an element relative to 1/12 mass of carbon 12.
Takes into account of percent abundance of each naturally occurring isotope and its individual mass
How are the percentage abundances of isotopes in a sample of element found?
Found experimentally using a mass spectrometer.
Sample placed in mass spectrometer and then sample is vaporised and then ionised to form positive ions. The ions are accelerated and heavier ions move more slowly and are more difficult to deflect than lighter ions soo the ions of each isotope are separated. The ions are detected on a mass spectrum as mass to charge ratio m/z. Each ion reaching the detector adds to the signal so the greater the abundance the larger the signal.
Mass to charge ratio is relative mass of ion divided by relative charge on ion.
^All of this is not part of spec just have an understanding
What is a binary compound?
Contains only 2 elements
First element name + second element name ending to -ide
Metal ion first
Polyatomic ions?
Ion containing atoms of more than one element such as CO3
What are the diatomic molecules and what is it
Containing two atoms bonded together
H2 N2 O2 F2 Cl2 Br2 I2 Basically all the halogens and oxygen and hydrogen
Ionic charge of ammonium
NH4
1+
Ionic charge of hydroxide
OH
1-
Ionic charge of nitrate
NO3
1-
Ionic charge of carbonate
CO3
2-
Ionic charge of sulfate
SO4
2-
What is mass spectrometry
Technique that can be used to study substances and gain info abt molecular mass
What is the mass charge ratio
M/z
Output from the mass spectrometer
Ionic charge of oxide
O
2-
Ionic charge of sulfide
S
2-
Ionic charge of zinc
Zn
2+
Ionic charge of silver
Ag
1+
Ionic charge of permanganate
MnO4
Otherwise known as manganate (VII)
1-
Ionic charge of dichromate
Cr2O7
2-
Ionic charge of thiosulfate
S2O3
2-
