Chemistry S1.1.1a | Free Chemistry Video | RevisionDojo
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Chemistry S1.1.1a
Learn Chemistry S1.1.1a in this free IB Chemistry video lesson for S1.1.1 Elements, Compounds and Mixtures.
Learn Chemistry S1.1.1a in this free IB Chemistry video lesson for S1.1.1 Elements, Compounds and Mixtures.
Summary of the Video
This video explores the classification of matter into elements, compounds, and mixtures, as well as methods for separating mixtures. It begins by defining matter as anything with mass and volume, dividing it into pure substances (elements and compounds) and mixtures (homogeneous and heterogeneous).
Key Points:
Elements:
Found on the periodic table, arranged by atomic number.
Composed of only one type of atom and cannot be chemically broken down.
Examples: Hydrogen (H), Oxygen (O).
Compounds:
Formed by chemically combining two or more elements in fixed ratios.
Compounds have properties distinct from their constituent elements.
Mixtures:
Contain multiple elements or compounds not chemically bonded and can be separated physically.
Homogeneous mixtures:
Uniform composition throughout, no visible boundaries.
Examples: Saltwater, air.
Heterogeneous mixtures:
Non-uniform composition with visible phases or boundaries.
Examples: Sand and water, oil and water.
Separation Techniques:
The video concludes by introducing methods to separate components of both homogeneous and heterogeneous mixtures, such as evaporation, distillation, and chromatography.
00:33
pure substances into elements and
00:35compounds. And then for mixtures,
00:38we have two types of
00:39mixtures which are homogeneous and
00:43heterogeneous. So in this video,
00:46we're going to start by
00:47looking at elements and compounds,
00:49and then we'll get into
00:50the differences between homogeneous and
00:54heterogeneous mixtures.
00:56So let's begin by looking
00:58at elements which can be
00:59found on the periodic table.
01:01Here we have a copy
01:02of the periodic table that's
01:03found in the chemistry data
01:05booklet. The periodic table contains
01:07all known elements and they're
01:10arranged in order of their
01:11atomic number which is the
01:13number of protons in the
01:14nucleus of an atom. So
01:16we have element 1, up
01:19to 118. Elements only made
01:23up of one type of
01:24atom
01:24and cannot be broken down
01:26into simpler substances by chemical
01:28means. You can think of
01:30elements as the building blocks
01:31of matter, all matter is
01:33made up of elements. Now
01:36of course, elements can combine
01:37to form compounds, which we
01:39look at next. So next
01:41we have compounds. Compounds are
01:43made up of two or
01:44more different elements chemically combined
01:47in fixed ratios. So here
01:49we have some examples of
01:50compounds, we have H2O,
01:52otherwise known as water. We
01:55have ethanol which is C2H5OH
01:58and then we have sodium
02:01chloride on the right which
02:03is otherwise known as salt.
02:06So these are all examples
02:07of compounds because they are
02:09made up of two or
02:10more different elements and they
02:11are chemically combined. In other
02:13words the atoms or ions
02:15are bonded by chemical bonds.
02:18The atoms also occur in
02:20fixed
02:20ratios for example in water
02:22there's one oxygen to two
02:25hydrogen atoms in ethanol there's
02:27two carbons to six hydrogens
02:30to one oxygen and in
02:32sodium chloride it's a one
02:34-to -one ratio of the
02:35ions the sodium ion and
02:37the chloride ion. An important
02:40point about compounds is that
02:41they have different properties from
02:43the elements from which they
02:45are made. For example here
02:47we have the chemical reaction
02:48between sodium and chlorine to
02:52produce sodium chloride and the
02:56properties of the elements. So
02:58we have sodium, which is
03:00a silver metal. We have
03:01chlorine, which is a poisonous
03:02gas. When they react together,
03:05they form sodium chloride, which
03:07is safe to eat in
03:09relatively small amounts. So the
03:12idea here is that the
03:13properties of the compound are
03:15very different from the elements
03:16from which the compound is
03:18made. So next we look
03:20at homogeneous and heterogeneous mixtures.
03:23So we have homogeneous on
03:24the left and heterogeneous on
03:27the right. Mixtures contain more
03:30than one element or compound
03:31in no fixed ratio. The
03:34components of a mixture are
03:35not chemically bonded together, therefore
03:37they can be separated by
03:39physical means. Some examples of
03:41homogeneous mixtures include salt water,
03:45and air. So salt water
03:50contains salt dissolved in water
03:52to make an aquaure solution
03:53so all aquaure solutions are
03:56homogeneous mixtures. Air is also
03:59a homogeneous mixture and it's
04:00basically a mixture of gases
04:02such as nitrogen, oxygen and
04:04some carbon dioxide amongst others.
04:08Homogeneous mixtures have no visible
04:10phases or boundaries so for
04:13For example, if you look
04:14at a glass of salt
04:15water, it looks like it's
04:17just pure water because you
04:20can't see the salt because
04:22the salt is dissolved in
04:24the water. They also have
04:26a constant composition throughout and
04:29this means that they are
04:32the same composition wherever you
04:34take the sample from. So
04:36if you take, for example,
04:38going back to the glass
04:39of salt water,
04:41You take some salt water
04:42from the top, if you
04:43take the salt water from
04:44the bottom, the composition of
04:46that salt water will be
04:48the same wherever you take
04:49it. So, moving on to
04:52heterogeneous mixtures. So, two examples
04:55are sand and water. If
04:57you ever try to mix
04:58sand and water together, you'll
05:00notice that the sand does
05:01not dissolve in the water.
05:02And the second example is
05:04oil and water. So, if
05:06you ever try to mix
05:07oil and water, you'll notice
05:08that the oils
05:09stays on top and the
05:10water stays at the bottom.
05:12So both these are examples
05:13of heterogeneous mixtures. So heterogeneous
05:17mixtures have visible phases or
05:19boundaries. If you look at
05:22a glass of oil and
05:23water, you notice the oil
05:25on the top, the water
05:26at the bottom. So that's
05:27a visible phase or a
05:28boundary between the two phases,
05:31the oil and the water.
05:33The same for sand and
05:34water, the sand will be
05:35at the bottom, the water
05:36at the top.
05:37visible phase or boundary between
05:39the sand and the water.
05:42And heterogeneous mixtures do not
05:44have a constant composition throughout.
05:49So if we look at
05:50this diagram here, if we
05:51take some sample from the
05:53lower portion of the mixture,
05:54it'll be the sand, for
05:57example. And if you take
05:58from the upper portion of
05:59the mixture, it'll be the
06:01water. So the composition is
06:03not the same throughout a
06:05heterogeneous
06:05this mixture. So next we're
06:07going to have a look
06:08at some separation methods to
06:10separate the components of a
06:11homogeneous and a heterogeneous mixture.
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