Atoms Test

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A fictitious element X is composed of 20.0% of the isotope X-46, 25.0% of the isotope X-47, and 55.0% of the isotope X-48. What would the atomic mass of this element be?

Consider an element Z that has two naturally occurring isotopes with the following percent abundances: 65.0% with a mass of 22.0 and 35.0% with a mass of 24.0. What is the average atomic mass of this element Z?

How many electrons are in an atom of Gold?

What is the atomic number for an element with 13 neutrons and a mass number of 24?

Use the periodic table to determine the number of neutrons in nitrogen-15

Which particle determines the atomic number of an element in its nucleus?

• neutrons

• electrons

• protons

• protons & neutrons

How do the isotopes Hydrogen-1 and Hydrogen-2 differ?

• the number of protons
• the number of electrons
• the number neutrons
• the average atomic mass

Which statement is NOT true?

• The nucleus of an atom has a positive charge.
• atoms are mostly empty space
• atoms of the same element can have different masses
• atoms of isotopes of an element have different numbers of protons