Download So where did all the matter on Earth come from - Bennatti

A Quick Intro/Review of a Little Basic Chemistry
Matter is made of atoms. If you take a sample of an element such as carbon and divide it into
smaller and smaller pieces, the smallest unit that would still have the characteristic properties of
carbon is an atom. Of course, an atom is much too small for you to see even with a light microscope.
http://www.es.ucsc.edu/~es10/classnotes/lectures/atomic.struct.jpg
There are two regions of an atom. A small dense center called the nucleus (plural nuclei) and
the region surrounding the nucleus called the electron cloud. The nucleus is composed of positively
charged particles called protons and neutral particles (particles with no charge) called neutrons.
Most of the mass of the atom is in this dense nucleus.
The electron cloud surrounding the nucleus is mostly empty space but contains negatively
charged particles called electrons.
Each element has a unique number of protons. The number of protons is its atomic number.
For example, hydrogen has the atomic number 1 meaning each hydrogen atom has one proton in its
nucleus. No other atom has one proton in its nucleus. Hydrogen is the simplest element. The
atomic number of helium is two. Each helium atom has two protons. No other element is made of
atoms with two protons in the nucleus.
Each element is represented with a chemical symbol. Most chemical symbols are one or two
letters. The first letter is always capitalized. If it has two or three letters only the first letter is
capitalized. For example the chemical symbol for the element magnesium is Mg. Note the letter g is
lower case. This is important as Co is the element cobalt but CO is the compound carbon monoxide.
When chemical reactions occur such as the reaction of hydrogen with oxygen to form water,
only the electrons in the electron cloud are involved. 2H2 + O2  2H2O During these
chemical reactions, electrons are either shared or transferred between atoms to create the bonds that
hold the atoms together. The identities of the elements do not change. You start with hydrogen and
oxygen atoms and you still have hydrogen and oxygen atoms after the chemical reaction has
occurred…they have simply bonded together to make a water molecule.
Nuclear reactions like those that occur in a nuclear power plant or in a star are very different
from chemical reactions. They are called nuclear reactions because they involve changes in the
nuclei of atoms. These changes in the nuclei of the atoms cause the atoms to change from one
element to another as the number of protons changes. We will talk about this a bit more later.
Review
Matching
1. ___ the number of protons in an atom
2.___ this is the small dense center of an atom
3.___ smallest unit of an element
4.____negatively charged subatomic particles
5.____positively charged subatomic particles
6.____subatomic particles with no charge
7.____occurs in stars
8. ____region surrounding the nucleus
9.____ involves the formation or breaking of bonds between atoms
a. atom
b. electrons
c. chemical reactions
d. neutrons
e. nuclear reactions
f. protons
g. atomic number
h. electron cloud
i. nucleus
Questions
1.
Use the periodic table in your planner, the periodic table in the front of the science classroom
or find a periodic table on the internet to answer the following questions.
1.
a. What is the atomic number of carbon?______
b. What does this tell you about carbon?
2.
3.
Carbon is:
a. an element;
b. a proton; c. a nuclear reaction;
d. an electron
a. What is the atomic number of fluorine? ______
b. What does this tell you about fluorine?
4.
Which element has the atomic number 5? ______
5.
How many protons does an oxygen atom contain?____
6.
Which element has the atomic number 3?_____
7.
Which subatomic particles are involved in the formation of chemical bonds?
8.
Which atom has the atomic number 26?
9.
a. What is the chemical symbol for the element nickel?
b. What is the atomic number of nickel?
c. How many protons does a nickel atom contain?
10.
Which is smaller a calcium atom or a strontium atom?
How do you know?