Chemistry - symbol equations

So we haven't covered this in class yet (get ahead amIright?) but when writing and balancing equations if you are not given a gap fill but just the word equation to refrence how do you know what amounts to use?
e.g. Calcium carbonate + nitric acid → Calcium Nitrate + water + Carbonate ... how do i know the quanities to make it balanced?
CaCO,3 + HNO,3 → ???
Do you have to pretty much memorise the Symbols for most equations - if so is there a resourse or cheat sheet I can revise those with🫠?

Balancing (non-redox) reactions using valences can be a bit challenging, but with a step-by-step approach it can be mastered. Here is a detailed method to help you balance (non-redox) reactions using valences.
1: Write down the unbalanced reaction, using the reaction in words.
You need to start by writing down the unbalanced reaction using the formulae of the different compounds:
CaCO3 + HNO3 = Ca(NO3)2 + CO2 + H2O
2: Identify the reactants and the products of the reaction.
The reactants (CaCO3 and HNO3) are on the left and the products (Ca(NO3)2, CO2 and H2O) are on the right. Make sure you understand the chemical formulae and the number of atoms of each element in each compound.
3: Counting valences
Look at the valence table here: http://www.vaxasoftware.com/doc_eduen/qui/valencia.pdf
You need to count the valence (oxidation number) of each element in the reactants and products. Valence is the number of electrons that an atom gains or loses to form a compound. The following rules can be used to determine valence and you have to learn the use of the periodic table of elements:
For example:
Group (1, 2, 13-18) elements typically have a valence of 1, 2 or 3.
Transition metals (groups 3-12) can have multiple valences, but typically have a valence of 2 or 3.
Halogens (group 17) typically have a valence of -1.
Oxygen has a valence of -2.
Nitrogen typically has a valence of -3.
For this reaction the valences are:
Ca: +2
C: +4
O: -2
N: -3
H: +1
4: Now you can start balancing the reaction
You need to start balancing the reaction one element at a time. Start with the element that appears in the smallest number of compounds. In this case it is calcium (Ca).
CaCO3 contains 1 atom of Ca and Ca(NO3)2 also contains 1 atom of Ca. To balance the Ca, add a coefficient of 1 before CaCO3:

Now you have to balance the C:
CaCO3 contains 1 C and CO2 also contains 1 C. To balance the C, there is no need to write any coefficients because they are equal (1).
So let's balance the O:
CaCO3 contains 3 O, while Ca(NO3)2 contains 6 O and H2O contains 2 O. To balance the O, we must always add the smaller coefficient (2).
To balance the O, add a coefficient of 2 before HNO3:

Now we have to balance the N:
HNO3 contains 1 N, but you have written 2 in front of HNO3, while Ca(NO3)2 contains 2 N. To balance the N, no coefficient is needed because the (NO3) groups of HNO3 contain 2 N, just as the (NO3) groups of Ca(NO3)2 contain 2 N.
Finally, we balance the H:
HNO3 contains 3 H, while H2O contains 2 H. To balance the H, add a coefficient of 2 (always the smaller of the two) before HNO3; to balance the H, add a coefficient of 2 before HNO3:

5: Now you can check the balanced reaction.
Once you added the coefficients, check the balanced reaction to make sure it is correct. Make sure that the number of atoms of each element is the same on both the reactant and product sides.
For this reaction

Ca: 1 (reactant) = 1 (product)
C: 1 (reactant) = 1 (product)
O: 3 (reactant) = 3 (product)
N: 2 (reactant) = 2 (product)
H: 4 (reactant) = 4 (product)
The reaction is now balanced!
Tips and tricks
Always start by balancing the element that appears in the smallest number of compounds.
Use the coefficients to balance the reaction rather than changing the subscripts.
Check the reaction several times to make sure it is balanced.
If you do not understand, use my text and tell me where you have doubts or difficulties in understanding.
Greetings from Italy.
Nitrotoluene