Any element in group 18 has eight valence electrons (except for helium, which has a total of just two electrons). Examples include neon (Ne), argon (Ar), and krypton (Kr). Oxygen, like all the other elements in group 16, has six valence electrons.
Answer:
Accuracy of a measured value refers to how close a measurement is to the correct value. The uncertainty in a measurement is an estimate of the amount by which the measurement result may differ from this value. Precision of measured values refers to how close the agreement is between repeated measurements.
Explanation:
They become more stable because they achieve a full outer shell of valence electrons with the magic number of 8.
Answer:
In the criss-cross method, the numerical value of the ion charge of the two atoms are crossed over, which becomes the subscript of the other ion. Using this technique, we will write the chemical formula of the given compounds.
Criss cross the absolute values to give Al2O3. To find the formula for magnesium oxide:- The oxidation number of Mg is +2 and oxygen is -2. Criss cross the absolute values to give Mg2O2In this example there is a common factor of 2 so divide by 2 to give MgO.
Answer:
Density of the copper = 8.94g/cm^3
Student A results = 7.3gm/cm^3 ,9.4 gm/cm^3 , 8.3gm/cm^3
Student B results = 8.4 gm/cm^3 , 8.8 gm/cm^3 , 8gm/cm^3
From the observations we conclude that
Student A's result is accurate but not precise as the trials noted are not close to each other.
Student B's result is accurate and precise as the trials noted are close to each other.
Mean density of student A = 7.3 + 9.4 + 8.3 /3 = 8.33gm/cm^3
Mean density of student B = 8.4 + 8.8 + 8 /3 = 8.4 gm/cm^3
both the densities of A and B are 0.5 away from the actual density.
