24.1% of all the isotopes of a an element have a mass of 75.23 amu, 48.7% have a mass of 74.61 amu, and 27.2% have a mass of 75.20 amu.
What is the average mass of this element?

• 74.92 amu
• 24.97 amu
• 75.01 amu
• 74.51 amu

Calcium has three different isotopes. One has a mass of 35.00 amu; another has a mass of 41.00 amu; and another has a mass of 40.00 amu. Which isotope is the most abundant of the three?

• 40.00 amu
• 41.00 amu
• 35.00 amu
• impossible to tell

What is the name of the atom pictured here?

• Nitrogen
• Nitrogen-15
• Nitrogen-7
• Nitrogen-8

Tags

NGSS.HS-PS1-1

the smallest particle of an element that retains all the properties of that element; is electrically neutral, spherically shaped, and composed of electrons, protons, and neutrons

• electron
• neutron
• atom
• proton

the weighted average mass of the isotopes of that element

• mass number
• atomic number
• nuclear equation
• atomic mass

the number of protons in an atom

• mass number
• atomic number
• atomic mass unit (amu)
• atomic mass

Tags

NGSS.HS-PS1-8

theory which states that matter is composed of extremely small particles called atoms; atoms are invisible and indestructible; atoms of a given element are identical in size, mass, and chemical properties; atoms of a specific element are different from those of another element; different atoms combine in simple whole-number ratios to form compounds; in a chemical reaction, atoms are separated, combined, or rearranged

• radioactive decay
• dalton's atomic theory
• nuclear equation
• radioactivity

Tags

NGSS.HS-PS1-7

a negatively charged, fast-moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atom's nucleus

• proton
• atom
• electron
• neutron

atoms of the same element with different numbers of neutrons

• isotopes
• atom
• cathode ray
• dalton's atomic theory

Tags

NGSS.HS-PS1-8

the number after an element's name, representing the sum of its protons and neutrons

• atomic mass
• mass number
• atomic mass unit (amu)
• atomic number

Tags

NGSS.HS-PS1-8