Atomic Structure and the Periodic Table

Question 1

Why were the alpha particles deflected in Geiger’s experiment and what did this conclude?

Answer 1

Because the nucleus of an atom and alpha particles are both positively charged, and so repel each other. This concluded that the nucleus is positively charged and was so much smaller than the rest of the atom, even though its mass is concentrated in the nucleus and being mostly empty space

Question 2

What is an isotope?

Answer 2

An atom with the same atomic number but different mass number (different number of neutrons)

Question 3

How would you calculate the relative atomic mass of an element with a given relative abundance?

Answer 3

Use the percentage of each and the mass number. Times them together from each isotope and divide it by 100.

Question 4

Why are the relative atomic masses of some elements decimals?

Answer 4

Some elements have isotopes so their RAMs are going to be mean values

Question 5

Why did Mendeleev’s gaps in his table help support his ideas?

Answer 5

It helped him predict the properties of undiscovered elements correctly

Question 6

Why were iodine and tellurium placed correctly before and after Mendeleev reversed their positions?

Answer 6

Before - order of increasing atomic mass and tellurium has a greater Ar value (128>127) to iodine and so was placed after it in the Periodic Table
After - iodine and tellurium did not match their group elements, and so Mendeleev swapped them to be lined up with other elements with similar chemical properties