Complete the table for a neutral atom of each element. Some...

Complete the table for a neutral atom of each element. Some labels may be used more than once, and some labels will not be used at all. Element name: argon, [ ], [ ] Symbol: [ ], [ ], Co Atomic number: [ ], 4, [ ] Mass number: 40, [ ], 59 Number of protons: [ ], [ ], [ ] Number of electrons: [ ], [ ], 27 Number of neutrons: [ ], 5, [ ] Answer Bank Ar 32 chromium 22 Be 70 cobalt 18 27 Ca beryllium 9 4

Transcript

00:03 Hi there.

00:03 In this question, we have a table to complete, and of course we can convert or we can supply the name or the symbol for an element if we know one or the other.

00:21 If you look at the periodic table and determine one or the other if we're given one.

00:28 If we are given neither one, what we can use is the atomic number.

00:34 Because the atomic number, we can look at the periodic table to determine which element that is.

00:41 And the atomic number is also equal to the number of protons.

00:49 Because the number of protons determines the identity of an atom.

00:54 So if we have either the atomic number or the element name or symbol or the number of protons, we can convert to each of the others.

01:03 Also, since these are atoms, they are neutral.

01:08 Since they are neutral, they're going to have the same number of protons as they have electrons.

01:15 Since protons are positively charged, electrons are negatively charged, these two are going to be equal.

01:22 So the number of protons will equal the number of electrons, rather.

01:27 And finally, i think the only thing that leaves is mass number and number of neutrons.

01:33 Well, mass number is equal to the number of protons plus the number of neutrons.

01:45 So if we know the number of protons, or we know the number of neutrons, or we know the mass number, if we know two of the three of these, we can get the third one.

01:58 Okay, so let's go ahead and start filling these in.

02:01 So in our first column, we have argon.

02:07 That's going to have the symbol, ar, and looking at the periodic table, its atomic number is 18.

02:18 We are given the mass number here as 40, so that's going to be useful.

02:23 Let's go on and do the number of protons next.

02:26 Remember, protons and atomic number are the same...

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