Calculating Average Atomic Mass

What is true about a neutral atom?

• The number of protons equal the number of neutrons
• The number of protons equal the number of electrons
• The number of neutrons equal the number of electrons
• The number of protons, neutrons, and electrons are all different

Tags

NGSS.MS-PS1-1

To calculate average atomic mass, you need

• the atomic mass of each isotope

• the percent abundance of each isotope

• the atomic mass and percent abundance of each isotope

• to find the average of the atomic masses of each isotope

Magnesium has 3 naturally occurring isotopes: Mg-24 (78.99% with a mass of 23.99 amu), Mg-25 (10.00% with a mass of 24.99 amu) , and Mg-26 (11.01% with a mass of 25.99 amu).  What is the average atomic mass of magnesium?

A neutral atom of the isotope ²⁶₁₂Mg would consist of

• 12 protons, 26 neutrons, 26 electrons
• 26 protons, 12 neutrons, 26 electrons
• 26 protons, 14 neutrons, 14 electrons
• 12 protons, 14 neutrons, 12 electrons

Tags

NGSS.MS-PS1-1

Isotopes are atoms of the same element that have the same number of __________ but different number of __________ . Therefore, isotopes of the same element have different masses. 

• protons, neutrons
• protons, electrons
• neutrons, protons
• electrons, protons

Tags

NGSS.HS-PS1-8

An element with 4.35% have a mass of 49.9461 amu, 83.79% have amass of 51.9405 amu, 9.50% have a mass of 52.9407 amu, and 2.36% have a mass of 53.9389amu.

Tags

NGSS.MS-PS1-1

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?

Tags

NGSS.MS-PS1-2

An element has two naturally occurring isotopes. One is 10.013 amu and is 19.9% abundant. The other is 11.01 amu and is 80.1% abundant. What is the average atomic mass? What element is it?