Atoms, compounds, molecules and equations Flashcards
What do metal atoms usually do during reaction
When metal atoms react, they tend to lose their outer electrons to form positive ions
How can you predict the charge of ions in group 1 and 2
If you look at the element in the periodic table. The group determines what charge it will be
How can you predict the charges on the ions in group 3 metals (aluminum)
It is difficult to determine the charge of ions in group 3. However we know that. Aluminum forms a charge of 3+.
Why are the charges of transition metals ions unusual
At the center of the periodic table, we have the transition metals. They are unusual as they can often form several positively charged ions
Why are the charges of transition metals ions unusual
At the center of the periodic table, we have the transition metals. They are unusual as they can often form several positively charged ions
What ion does silver form
silver forms Ag+
What ion does zinc form
Zn^2+
What happens when a non-metal atoms form ions
When non-metal atoms form ions, they tend to gain electrons and form negative ions
What happens to the name of the non-metal atom when it turns into an ion
The name of the ion turns to ide at the ends (suffix)
It only changes to ide if the non-metal has reacted with one other elements e.g (Lithium chloride)
How can we use the periodic table to work out the charge on the non-metal ion produced
The group 5 elements nitrogen and phosphorus forms ions with a 3- charge
The group 6 elements oxygen and sulfur form ions with a 2- charge
The groups 7 elements form ions with a 1- charge
What are the charges of the following non-metal ions :
Hydrogen, Ammonium, Hydroxide , Nitrate, Carbonate, Sulfate
H +
NH4 +
OH -
NO3 -
CO3 2-
SO4 2-
What do all these ions apart from hydrogen have in common:
Hydrogen Ammonium, Hydroxide , Nitrate, Carbonate, Sulfate
All these ions apart from the hydrogen ion contain two different elements. These are called polyatomic ions
Key facts to know about ionic compounds:
The charges of the individual ions must cancel out to produce an overall charge of zero
The charges of ions are never written down when we write the formula of an ionic compound
The little number to the right of brackets multiple everything within it
How does zinc oxide get its charge
The 2+ charge on the zinc ion is canceled out by the 2- charge of the oxide ion.
Therefore, the compound has an overall charge of zero. Thus has a formula of ZnO
What is the formula of:
ammonium nitrate
Lithium sulfide
Aluminum oxide
NH4NO3
Li2S
Al2O3
Work out the formula of calcium nitrate
Ca = 2+
NO = 3-
Ca(NO3)2
Explain what are isotopes
Isotopes are atoms of the same elements with different number of neutrons and different masses
Key ideas of isotopes:
All isotopes of an element react in the same way as they all have the same electron configuration
The abundance of isotopes tell his how common each isotope is.
Explain the function of the mass spectrometer
It determines the mass number and abundance of isotopes
Explain how to interpret a mass spectrum
The peaks on the graph determine the number of isotopes
The y-axis shows the relative abundance of isotopes of the same elements which give the percentage of the total. (Often shown at the top of the peak)
On the x-axis there is an m/z ratio. This is the ratio of the mass of each ion and its charge. Almost all ions have a single positive charge. (Interpreted as the Relative mass of the ion)
How are the extremely small masses of atom solved
This problem is solved through using relative mass
Explain relative masses
Masses in Chemistry are relative to carbon-12 which is an isotope of carbon.
They are called relative masses as they are relative to carbon-12. The atoms of carbon-12 has a mass of 1. 1/12th of the mass of this atom is counted as 1
Define relative isotopic masses
Relative isotopic mass is defined as the mass of an atom of an isotope compared with 1/12th the mass of carbon-12
Key points of relative isotopic mass:
There is one relative isotopic mass for each isotope of an element
Relative isotopic mass is always a whole number. It is never a decimal
Relative isotopic mass has no units.
Define relative atomic mass
Relative atomic mass is the weighted mean mass of an atom of an element compared with 1/12th the mass of carbon-12
Key points of relative atomic mass :
The mean is weighted for the abundance of each isotope. How common an isotope is.
Relative atomic mass has no units
Virtually all of the relative atomic masses are not whole numbers. This is because it is a mean
How to calculate relative atomic mass
(Relative isotopic mass of isotope 1 X percentage abundance of isotope 1 )
+
(Relative isotopic mass of isotope 2 X percentage abundance of isotope 2 )
Ar=———————————————————————————-
100
What does the molecular formula show
It tells us the elements in a molecule and the number of atoms in each element
Complications of molecular formula
It does not give us information about the structure of the molecule.
Complications of molecular formula
It does not give us information about the structure of the molecule.
What does the empirical formula show
It tells us the simplest whole-number ratio of the atoms of each element in a compound
Why is the molecular formula not used for a giant ionic lattice
Ionic compounds form crystals consisting of a giant ionic lattice. These contain a vast number of ions.
It is not practical to write the formula showing the actual number of atoms in each element
(Number of atoms is extremely large / a larger crystal would contain more atoms than small crystals)
How can the relative molecular mass be calculated
The relative atomic masses of a molecule is added together to calculate the relative molecular mass
Define relative molecular mass
The relative molecular mass is defined as the weighted mean mass of a molecule compared with 1/12th the mass of an atom of carbon-12
It has the symbol of Mr
Key ideas to calculate relative molecular mass
We do not use large number to calculate relative molecular mass. It only applies to one molecule.
How to calculate the relative formula mass
It is calculated the same ways as relative molecular mass. However, the empirical formula of the chemical is used.
When is relative atomic and molecular mass used
It is used for small covalent molecules
When is empirical formula or relative formula mass used
When giant ionic structures are being used
