2) Elements: Mass and Atomic Numbers

What is the atomic number?

the number of protons in the nucleus of an atom

What is the number of protons in the nucleus of an atom defined as?

the atomic number

What do atomic numbers identify?

elements

What identifies elements?

atomic numbers

What does changing the number of protons do?

change the identity of the element

What changes the identity of the element?

changing the number of protons

Where are atomic numbers listed as?

a subscript on the bottom, to the left side of an element’s chemical symbol

What is listed as a subscript on the bottom, to the left side of an element’s chemical symbol?

atomic numbers

What is the mass number?

the sum of the protons and neutrons in the nucleus of an atom

What is the sum of the protons and neutrons in the nucleus of an atom?

the mass number

Mass number - atomic number = _.

the number of neutrons in the nucleus of an atom

_ - _ = the number of neutrons in the nucleus of an atom

mass number - atomic number

What are isotopes?

different atoms of the same element that can have different numbers of neutrons

What are different atoms of the same element that can have different numbers of neutrons called?

isotopes

What are mass numbers listed as?

a superscript on the top, to the left side of an element’s chemical symbol

What are listed as a superscript on the top, to the left side of an element’s chemical symbol?

mass numbers

What gives the mass of an individual atom in amu?

the mass number

What does the mass number give the mass of?

an individual atom in atomic mass units

What does amu stand for?

atomic mass units

What stands for atomic mass units?

amu

1 amu = _?

1.66 × 10-27 kg

_ = 1.66 × 10-27 kg

1 amu

Why are atomic masses in amu are never whole numbers?

because most elements exist in nature as a combination of different isotopes

What is natural abundance?

the percent of each isotope relative to the whole

What is the percent of each isotope relative to the whole defined as?

natural abundance