Download Classifying Matter

Classifying
Matter
Elements, Compounds
or Mixtures
Overview
Structure of an atom
Borh’s Model
Subatomic particles
Nucleus
Electron shells/orbitals
Elements, Compounds, Mixtures
Structure of the Atom
Are there pieces of matter that are smaller than
atoms?
Atoms are composed of subatomic particles called
electrons, protons, and neutrons.
Scientists call the center region of the atom the
nucleus. The nucleus in a cell is a thing. The nucleus
in an atom is a place where you find protons and
neutrons. The electrons are always found whizzing
around the center in areas called shells or orbitals.
Electrons have a negative charge and protons have a
positive charge whereas neutrons have no charge.
They are neutral. Due to the presence of equal
number of negative electrons and positive protons,
the atom as a whole is electrically neutral.
Bohr’s Model
In order to explain the stability of an atom,
Neils Bohr gave a new arrangement of
electrons in the atom in 1913. According to
Neils Bohr, the electrons could revolve around
the nucleus in only 'certain orbits' (energy
levels), each orbit having a different radius.
Orbitals
The center of the atom is called the nucleus.
Electrons are found in areas called shells. A
shell is sometimes called an energy level.
Shells are areas that surround the center of
an atom.
Each of those shells has a name (K, L, M, N,
O, P, Q).
There are a couple of ways that atomic shells
are described. The most general terms are
basic regions where you find electrons.
Chemists use the letters K, L, M, N, O, P, and
Q. The "K" shell is the one closest to the
nucleus, and "Q" is the farthest away.
Elements
Elements are the building blocks for all matter.
As you probably know, the periodic table is organized
like a big grid. The elements are placed in specific
locations because of the way they look and act. If you
have ever looked at a grid, you know that there are
rows (left to right) and columns (up and down). The
periodic table has rows and columns, and they each
mean something different.
We sometimes use the terms atom and element to
mean the same thing. Remember that atom is the
general term. Everything is made of atoms. The term
element is used to describe atoms with specific
characteristics. There are almost 120 known elements.
Compounds
Compounds are groups of two or more elements that are
bonded together. You have also seen us use the word molecule.
Molecule is the general term used to describe atoms
connected by chemical bonds. Every combination of atoms is a
molecule. Compounds happen with atoms from different
elements. So, all compounds are molecules, because they have
bonds between the atoms, like in water (H2O).
However, not all molecules are compounds because
sometimes the atoms are of the same element. Hydrogen gas
(H2) is a good example of a molecule that is not a compound.
Compounds
The process of naming compounds is just a set of rules.
When you have two different elements, there are usually only two
words in the compound name. The first word is the name of the
first element. The second word tells you the second element and
how many atoms there are in the compound. The second word
usually ends in IDE. That's the suffix. When you are working with
non-metals like oxygen (O) and chlorine (Cl), the prefix (section at
the beginning of the word) of the second element changes based
on how many atoms there are in the compound.
ures
Mixt
Mixtures are absolutely everywhere you look. Most
things in nature are mixtures. Look at rocks, the ocean, or
even the atmosphere. They are all mixtures, and mixtures
are about physical properties, not chemical ones. That
statement means the individual molecules enjoy being
near each other, but their fundamental chemical structure
does not change when they enter the mixture.
Scientists say that solutions are homogenous mixtures.
Everything in a solution is evenly spread out and mixed
together.
Let's compare sugar in water (H2O) to sand in water.
Sugar dissolves and is spread throughout the glass of water.
The sand sinks to the bottom. The sugar-water could be
considered a solution. The sand-water combination is a
heterogeneous mixture.
http://www.brainpop.com/science/matterandchemistry/
compoundsandmixtures/