Choosing resistor for an op-amp
Whats the difference between 1ohm &amp; 10ohm resistors or 1kohm and 10kohm resistors?

Consider the voltage at the inverting input \$V_{IN-}\$ when looking at the circuit: -

We know that an op-amp has massive open-loop gain hence, for practical reasons (in most op-amp circuits) we can assume that the voltage at \$V_{IN-}\$ equals the voltage at \$V_{IN+}\$ and, because \$V_{IN+}\$ is 0 volts, we can regard the feedback resistor (R2) as loading the output of the op-amp.
Let me repeat that: -
$$\color{red}{\boxed{\text{the basic op-amp load is the feedback resistor R2}}}$$
It's then a simple case of reading the data sheet to see how much current an op-amp output can produce - you'll generally find that it's about 10 mA. It might only be 5 mA or it might be 25 mA but, it's in that rough area for 99% of all op-amps.
So, if your output voltage might be as high as 10 volts then work out what the minimum value of R2 should be. So, 10 volts divided by 10 mA equals 1000 ohms. So, we should aim to ensure that R2 is significantly greater than 1000 ohms.
If you are planning on an external load of 2 kohm then the minimum value for the feedback resistor is 2 kohm. From this you calculate what R1 needs to be to meet your amplification requirements.