yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

Worked example: using the mass number equation | High school chemistry | Khan Academy


less than 1m read
·Nov 10, 2024

Hi everyone. In this video, we're going to practice using the mass number equation. This equation represents the fact that the mass number of an atom is equal to its number of protons plus its number of neutrons.

Let's use the mass number equation to answer the following question: How many neutrons are in an isotope of sodium with the following notation? To answer this question, we'll first need to rearrange our mass number equation to solve for the number of neutrons. Pause the video and take a moment to try this for yourself.

The rearranged equation is as follows: The number of neutrons equals the mass number minus the number of protons. Based on this notation, we know that this sodium isotope has a mass number of 23 and an atomic number of 11. If we subtract the atomic number 11 from the mass number 23, we're left with 12, which is the number of neutrons in this sodium isotope.

Okay, more practice! This time with an isotope of platinum: How many neutrons does this isotope have based on the following notation: PT-195? Again, we'll need to use the rearranged mass number equation to solve for the number of neutrons. This particular notation provides the chemical symbol of platinum and its mass number.

We can look up platinum on the periodic table to find its atomic number, which is 78, meaning that every platinum atom has 78 protons. We can subtract the atomic number 78 from the mass number 195 to get 117. So this isotope of platinum has 117 neutrons.

More Articles

View All
Exclusive: Russian Foreign Minister Sergey Lavrov Describes the War With the US and How to End It
Minister Le, thank you for doing this. Um, do you believe the United States and Russia are at war with each other right now? I wouldn’t say so, and uh, in any case, this is not what we want. Uh, we would like to have normal relations with all our neighbo…
Theoretical probability distribution example: multiplication | Probability & combinatorics
We’re told that Kai goes to a restaurant that advertises a promotion saying one in five customers get a free dessert. Suppose Kai goes to the restaurant twice in a given week, and each time he has a one-fifth probability of getting a free dessert. Let X r…
Fuzzy Pancakes and More! LÜT #19
Macaroni and cheese scented air fresheners and bacon and egg earrings. It’s episode 19 of LÜT. This clock tells the correct time, except it runs backwards. And Thailand Unique will sell you a bottle of whiskey with a cobra in it, delicious chocolate cove…
Circuit terminology | Circuit analysis | Electrical engineering | Khan Academy
In this video, we’re going to talk about some terminology that we use to talk about how circuits are put together. In previous videos, we’ve talked about the components or elements that are used to make up circuits. So, for example, a resistor, capacitor,…
Classifying shapes of distributions | AP Statistics | Khan Academy
What we have here are six different distributions, and what we’re going to do in this video is think about how to classify them or use the words that people typically use to classify distributions. So let’s first look at this distribution right over here…
Is Glass a Liquid?
In 1994, a massive earthquake shook the Northridge suburb of Los Angeles, killing 57 people and injuring over 5000. The cost of damages was in excess of $20 billion. It’s earthquakes like this one that make us question just how solid is the earth beneath …