[Script Info]
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[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.66,0:00:02.79,Default,,0000,0000,0000,,- [Instructor] We know that\Neverything in the universe
Dialogue: 0,0:00:02.79,0:00:04.86,Default,,0000,0000,0000,,is composed of atoms,
Dialogue: 0,0:00:04.86,0:00:07.44,Default,,0000,0000,0000,,but not all atoms are the same.
Dialogue: 0,0:00:08.34,0:00:11.88,Default,,0000,0000,0000,,There are many different types\Nof atoms called elements,
Dialogue: 0,0:00:11.88,0:00:16.05,Default,,0000,0000,0000,,each with a unique set of\Nphysical and chemical properties.
Dialogue: 0,0:00:16.05,0:00:18.90,Default,,0000,0000,0000,,Many elements are\Nprobably familiar to you.
Dialogue: 0,0:00:18.90,0:00:22.11,Default,,0000,0000,0000,,Oxygen and carbon, for\Nexample, are elements,
Dialogue: 0,0:00:22.11,0:00:23.64,Default,,0000,0000,0000,,and so is gold.
Dialogue: 0,0:00:25.17,0:00:27.15,Default,,0000,0000,0000,,Others may be less familiar
Dialogue: 0,0:00:27.15,0:00:30.24,Default,,0000,0000,0000,,such as bismuth, xenon, and osmium.
Dialogue: 0,0:00:32.34,0:00:34.29,Default,,0000,0000,0000,,A particular element is identified
Dialogue: 0,0:00:34.29,0:00:36.75,Default,,0000,0000,0000,,by the number of protons in its atoms.
Dialogue: 0,0:00:36.75,0:00:40.08,Default,,0000,0000,0000,,And the number of protons\Nin the nucleus of an atom
Dialogue: 0,0:00:40.08,0:00:43.98,Default,,0000,0000,0000,,is its atomic number,\Nrepresented by the symbol Z.
Dialogue: 0,0:00:45.00,0:00:49.05,Default,,0000,0000,0000,,For example, helium has\Nan atomic number of two.
Dialogue: 0,0:00:49.05,0:00:53.52,Default,,0000,0000,0000,,That means that every\Nhelium atom has two protons.
Dialogue: 0,0:00:53.52,0:00:56.94,Default,,0000,0000,0000,,And here's another example, iron,
Dialogue: 0,0:00:56.94,0:00:59.25,Default,,0000,0000,0000,,its atomic number is 26,
Dialogue: 0,0:00:59.25,0:01:03.00,Default,,0000,0000,0000,,so every iron atom has 26 protons.
Dialogue: 0,0:01:03.93,0:01:06.48,Default,,0000,0000,0000,,An element's atomic\Nnumber can also tell us
Dialogue: 0,0:01:06.48,0:01:10.20,Default,,0000,0000,0000,,the number of electrons in a\Nneutral atom of an element.
Dialogue: 0,0:01:10.20,0:01:14.43,Default,,0000,0000,0000,,Remember, equal and opposite\Ncharges cancel each other out
Dialogue: 0,0:01:14.43,0:01:16.20,Default,,0000,0000,0000,,so to be neutral,
Dialogue: 0,0:01:16.20,0:01:19.32,Default,,0000,0000,0000,,an atom must have an\Nequal number of protons,
Dialogue: 0,0:01:19.32,0:01:21.21,Default,,0000,0000,0000,,which have a charge of 1+,
Dialogue: 0,0:01:21.21,0:01:23.58,Default,,0000,0000,0000,,and electrons, which have a charge of 1-.
Dialogue: 0,0:01:24.57,0:01:27.90,Default,,0000,0000,0000,,This means that our helium\Natom must have two electrons
Dialogue: 0,0:01:27.90,0:01:31.68,Default,,0000,0000,0000,,and our iron atom must have 26 electrons.
Dialogue: 0,0:01:33.21,0:01:34.71,Default,,0000,0000,0000,,All of the known elements
Dialogue: 0,0:01:34.71,0:01:37.77,Default,,0000,0000,0000,,are organized according\Nto their atomic numbers
Dialogue: 0,0:01:37.77,0:01:39.66,Default,,0000,0000,0000,,in the periodic table.
Dialogue: 0,0:01:39.66,0:01:42.24,Default,,0000,0000,0000,,The periodic table lists the elements
Dialogue: 0,0:01:42.24,0:01:44.46,Default,,0000,0000,0000,,in order of increasing atomic number
Dialogue: 0,0:01:44.46,0:01:48.63,Default,,0000,0000,0000,,as you go from left to right\Nand from top to bottom.
Dialogue: 0,0:01:48.63,0:01:51.57,Default,,0000,0000,0000,,The elements are further\Norganized into columns
Dialogue: 0,0:01:51.57,0:01:53.34,Default,,0000,0000,0000,,based on their properties.
Dialogue: 0,0:01:53.34,0:01:54.96,Default,,0000,0000,0000,,Elements in the same column
Dialogue: 0,0:01:54.96,0:01:58.26,Default,,0000,0000,0000,,tend to have similar physical\Nand chemical properties.
Dialogue: 0,0:01:59.37,0:02:03.15,Default,,0000,0000,0000,,Every element is represented\Nby a chemical symbol,
Dialogue: 0,0:02:03.15,0:02:05.79,Default,,0000,0000,0000,,a unique one or two letter abbreviation
Dialogue: 0,0:02:05.79,0:02:08.31,Default,,0000,0000,0000,,that appears below the\Nelement's atomic number
Dialogue: 0,0:02:08.31,0:02:10.20,Default,,0000,0000,0000,,on the periodic table.
Dialogue: 0,0:02:10.20,0:02:11.28,Default,,0000,0000,0000,,Many chemical symbols
Dialogue: 0,0:02:11.28,0:02:14.10,Default,,0000,0000,0000,,are based on the English\Nname for an element.
Dialogue: 0,0:02:14.10,0:02:17.13,Default,,0000,0000,0000,,For example, the symbol for hydrogen is H,
Dialogue: 0,0:02:17.13,0:02:19.41,Default,,0000,0000,0000,,and the symbol for aluminum is Al.
Dialogue: 0,0:02:20.25,0:02:21.93,Default,,0000,0000,0000,,But some chemical symbols
Dialogue: 0,0:02:21.93,0:02:24.66,Default,,0000,0000,0000,,are based on the Latin\Nname for the element.
Dialogue: 0,0:02:24.66,0:02:28.05,Default,,0000,0000,0000,,For example, the symbol for lead is Pb,
Dialogue: 0,0:02:28.05,0:02:32.10,Default,,0000,0000,0000,,which actually comes from\Nits Latin name plumbum.
Dialogue: 0,0:02:32.10,0:02:34.20,Default,,0000,0000,0000,,Notice that whenever the chemical symbol
Dialogue: 0,0:02:34.20,0:02:36.33,Default,,0000,0000,0000,,for an element has two letters,
Dialogue: 0,0:02:36.33,0:02:38.79,Default,,0000,0000,0000,,the second letter is written in lowercase.
Dialogue: 0,0:02:40.14,0:02:42.36,Default,,0000,0000,0000,,All of this information is contained
Dialogue: 0,0:02:42.36,0:02:45.93,Default,,0000,0000,0000,,inside of each element's\Nbox on the periodic table.
Dialogue: 0,0:02:45.93,0:02:49.62,Default,,0000,0000,0000,,For example, here's the box\Nfor the element nitrogen.
Dialogue: 0,0:02:49.62,0:02:50.85,Default,,0000,0000,0000,,At the top of the box
Dialogue: 0,0:02:50.85,0:02:54.48,Default,,0000,0000,0000,,is nitrogen's atomic\Nnumber, which is seven.
Dialogue: 0,0:02:54.48,0:02:56.01,Default,,0000,0000,0000,,Remember that this is equal
Dialogue: 0,0:02:56.01,0:02:59.52,Default,,0000,0000,0000,,to the number of protons\Nin each atom of nitrogen
Dialogue: 0,0:02:59.52,0:03:02.46,Default,,0000,0000,0000,,as well as the number of electrons.
Dialogue: 0,0:03:02.46,0:03:05.94,Default,,0000,0000,0000,,Below that is nitrogen's\Nchemical symbol, N,
Dialogue: 0,0:03:05.94,0:03:07.92,Default,,0000,0000,0000,,followed by its name.
Dialogue: 0,0:03:07.92,0:03:10.02,Default,,0000,0000,0000,,Often, you'll also see another number
Dialogue: 0,0:03:10.02,0:03:12.36,Default,,0000,0000,0000,,listed at the bottom of an elements box,
Dialogue: 0,0:03:12.36,0:03:15.12,Default,,0000,0000,0000,,which has to do with atomic mass.
Dialogue: 0,0:03:15.12,0:03:18.60,Default,,0000,0000,0000,,We'll cover details about\Nthis and another video.
Dialogue: 0,0:03:18.60,0:03:20.07,Default,,0000,0000,0000,,What's neat about having
Dialogue: 0,0:03:20.07,0:03:22.23,Default,,0000,0000,0000,,all of this information in one place
Dialogue: 0,0:03:22.23,0:03:25.74,Default,,0000,0000,0000,,is that if we know one\Ndetail about an element,
Dialogue: 0,0:03:25.74,0:03:29.70,Default,,0000,0000,0000,,either it's atomic number,\Nchemical symbol, or a name,
Dialogue: 0,0:03:29.70,0:03:31.77,Default,,0000,0000,0000,,we can often use the periodic table
Dialogue: 0,0:03:31.77,0:03:34.23,Default,,0000,0000,0000,,to find out the other details.
Dialogue: 0,0:03:34.23,0:03:36.72,Default,,0000,0000,0000,,Let's take a look at a few examples.
Dialogue: 0,0:03:36.72,0:03:39.66,Default,,0000,0000,0000,,Say we have the element phosphorus,
Dialogue: 0,0:03:39.66,0:03:42.87,Default,,0000,0000,0000,,what is its atomic number\Nand chemical symbol?
Dialogue: 0,0:03:44.07,0:03:45.96,Default,,0000,0000,0000,,Looking through the periodic table,
Dialogue: 0,0:03:45.96,0:03:47.46,Default,,0000,0000,0000,,we can find phosphorus
Dialogue: 0,0:03:47.46,0:03:50.49,Default,,0000,0000,0000,,and see that its atomic number is 15
Dialogue: 0,0:03:50.49,0:03:52.77,Default,,0000,0000,0000,,and its chemical symbol is P.
Dialogue: 0,0:03:53.64,0:03:55.65,Default,,0000,0000,0000,,Let's do another example.
Dialogue: 0,0:03:55.65,0:03:59.16,Default,,0000,0000,0000,,Say we know the chemical symbol Hg,
Dialogue: 0,0:03:59.16,0:04:00.78,Default,,0000,0000,0000,,what is this element's name
Dialogue: 0,0:04:00.78,0:04:03.24,Default,,0000,0000,0000,,and how many protons does it have?
Dialogue: 0,0:04:04.32,0:04:07.68,Default,,0000,0000,0000,,Here is the symbol Hg\Non the periodic table.
Dialogue: 0,0:04:07.68,0:04:09.12,Default,,0000,0000,0000,,Its name is mercury,
Dialogue: 0,0:04:09.12,0:04:11.04,Default,,0000,0000,0000,,and its atomic number is 80
Dialogue: 0,0:04:11.04,0:04:13.59,Default,,0000,0000,0000,,so it has 80 protons.
Dialogue: 0,0:04:14.79,0:04:16.23,Default,,0000,0000,0000,,Let's reveal.
Dialogue: 0,0:04:16.23,0:04:17.67,Default,,0000,0000,0000,,The universe is made up
Dialogue: 0,0:04:17.67,0:04:20.43,Default,,0000,0000,0000,,of different types of\Natoms called elements,
Dialogue: 0,0:04:20.43,0:04:23.49,Default,,0000,0000,0000,,and these elements are\Norganized by atomic number
Dialogue: 0,0:04:23.49,0:04:25.41,Default,,0000,0000,0000,,in the periodic table.
Dialogue: 0,0:04:25.41,0:04:29.25,Default,,0000,0000,0000,,So, the next time that you\Nstare up at the starry sky,
Dialogue: 0,0:04:29.25,0:04:33.15,Default,,0000,0000,0000,,you know that everything out\Nthere is made up of elements.