Transcript
Page 1: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

Atoms

- the smallest unit of an element

Page 2: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms).

Atoms are so small they cannot be seen with a microscope.

Page 3: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

• The nucleus contains two types of particles: protons and neutrons.

Structure of the Atom

• The center of the atom is called the nucleus.

Page 4: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

Structure of the Atom

• Protons have a positive charge (+).

++• Neutrons have no charge. They are neutral.

Page 5: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

Structure of the Atom, cont’d• Electrons are

always moving or spinning around the nucleus, like planets orbiting the sun.

• The space where the electrons orbit is called the electron cloud.

Page 6: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

Structure of the Atom, cont’d• Electrons have a

negative (-) charge.

• Electrons are much smaller than protons.

Page 7: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

• The number of protons in an atom equals the number of electrons in an atom. Therefore an atom is electrically neutral.

# protons = # electrons

• What makes atoms different from one another is the number of protons, neutrons and electrons that they have.

Page 8: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

1. Label the picture of an atom using the following codes:

P – Proton

N – Neutron

E - Electrons

2. Color the protons blue.

3. Color the neutrons red.

4. Color the electrons brown.

5. Write the charges beside each one.

Structure of an Atom

Page 9: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

1. Label the picture of an atom using the following codes:

P – Proton

N – Neutron

E - Electrons

2. Color the protons blue.

3. Color the neutrons red.

4. Color the electrons brown.

5. Write the charges beside each one.

PP N

N

E

E

+

+ o

o

Structure of an Atom

Page 10: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

Atomic Number & Atomic Mass

Page 11: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

12.0116

Ccarbon

• The periodic table includes each element’s:– atomic number

– atomic mass

– symbol

– name

Page 12: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

Atomic Number

• The atomic number is the number of protons an element has.

• The periodic table lists elements in order by their atomic number.

• Remember, the number of protons is the same as the number of electrons.

Page 13: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

Atomic Mass

• The atomic mass (also called mass number) is the weight of one atom of the element.

• Atomic mass will also give you the average number of neutrons in the nucleus by the following formula:

# protons + # neutrons = atomic mass

Page 14: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

• What is the atomic number? 9

9

9

19

10

• How many protons?

• How many electrons?

• What is the atomic mass?

• How many neutrons?

19.009

Ffluorine

Page 15: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

Isotopes

• All atoms of a certain element will always contain the same number of protons, however the number of neutrons can vary.

• Isotopes are atoms that have the same number of protons, but different numbers of neutrons.

Page 16: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

Isotopes

• Carbon-12 has 6 protons and 6 neutrons. Carbon-14 has 6 protons and 8 neutrons.

• The atomic mass is an average of the isotopes so is not always a whole number.

• Isotopes are useful in determining age of fossils, diets of animals, and origins of wood.

Page 17: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

Atomic Mass

• Scientists have chosen the most common isotope of carbon (carbon-12) as a reference.

Page 18: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

• An atom of carbon-12 is assigned a mass of 12 atomic mass units (amu).

• The masses of all other atoms are compared with this mass.

Page 19: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

• One atomic mass unit is 1/12 the mass of a carbon-12 atom.

• The mass of an atom expressed in atomic mass units is called its atomic mass.

Page 20: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

• The atomic mass of an element found in the periodic table is actually calculated from the masses of the element’s isotopes.

• It is a weighted average of the masses of the isotopes – you must take into consideration the percent abundance of each element.

Page 21: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

• Example:

• There are two isotopes for lithium: lithium-6 makes up 7.4% of all lithium atoms and lithium-7 makes up the other 92.6%.

• Calculate the average atomic mass.

Page 22: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

• SOLUTION:

(6amu x 0.074) + (7amu x 0.926) = 0.44 + 6.482

= 6.922 = 6.9amu

Page 23: Atoms - the smallest unit of an element Each element is made up of only one type of atom (the element Carbon is only made up of carbon atoms). Atoms

Now it’s your turn……


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