In what directions (on the periodic table) does atomic size increase?
As you go down in a group, size increases, and as you go LEFT size increases. Size decreases as one goes right within a period.
http://www.sparknotes.com/chemistry/fundamentals/atomicstructure/section3.rhtml
Thanks! That helps alot!
What is more electronegative: oxygen or arsenic?
oxygen is about 3.5; As is about 2.
To determine which element is more electronegative, you can refer to a periodic table that lists the electronegativity values of various elements.
In this case, oxygen has an electronegativity value of about 3.5, while arsenic has an electronegativity value of about 2. Therefore, oxygen is more electronegative than arsenic.
You can find more information about electronegativity values of elements in reference books or online chemistry resources.