Exam 2: Atoms, molecules, and Ions

A proton is approximately

One mole of which element has the smallest mass?

The horizontal rows of the periodic table are called

What group of elements does the shaded area in the following periodic table indicate?

Na₂O is named

Iodine is an example of

Elements are classified as metals,nonmetals,or semimetals.At room temperature a certain element exists as a dull yellow solid that is a poor conductor of electricity and is brittle.This element is most likely a ________.

In which of the following sets do all species have the same number of protons?

How many electrons are in a neutral atom of iodine-131?

The thiosulfate ion is

Which element has the chemical symbol,Pb?

-Which of the above drawings represents an Ar atom?

Use the periodic table below to answer the following questions. -Which elements commonly form cations?

. -If shaded and unshaded spheres represent atoms of different elements,which of the above drawings most likely represents a molecular compound at room temperature and a pressure of 1 atm?

KH₂PO₄ is

What is the chemical formula for radium hydride?

What group of elements does the shaded area in the following periodic table indicate?

A sample of pure calcium fluoride with a mass of 15.0 g contains 7.70 g of calcium.How much calcium is contained in 35.0 g of calcium fluoride?

The formula of thallium(III)selenide contains ________ thallium(III)and ________ selenide ions.

-Which of the above drawings represents a pure compound?