2. Atoms & Elements

Which element has atoms that contain exactly 11 protons?

Which of the following is the basic unit of a chemical element?

An atom has an atomic number of 15 and a mass number of 31. How many protons are present in this atom?

Which of the following statements about the molecule Be_2 is correct?

How many neutrons are present in the most abundant isotope of boron?

What is the atomic number of lithium?

An atom with 10 electrons must have how many electron shells?

How many neutrons are present in an atom of chlorine-35?

Calcium has an atomic number of 20 and its most common isotope has a mass number of 40. How many neutrons are present in this isotope of calcium?

Which statement correctly describes the nucleus of the atom?

How many atoms are present in one molecule of HNO3?

Which of the following statements is true about a neutral atom of silicon?

Which of the following best describes what an electron cloud represents in an atom?

Carbon has an atomic number of 6. What can you conclude about carbon from this fact?

Which of the following statements about a neutral atom is correct?