protons and neutrons are responsible for most of the atomic mass of an atom, while electrons...

Inside the Atom

Let’s Investigate the Atom

Atoms are composed of three type of particles: SUBATOMIC PARTICLES: protons, neutrons, and electron.

Protons and neutrons are responsible for most of the atomic mass of an atom, while electrons contribute a very small amount of mass(9.108 X 10-28 grams).

What makes up the atom?

Protons and neutrons reside in the nucleus.

Protons have a positive (+) charge, neutrons have no charge. They are neutral.

Electrons are in orbitals, or electron clouds, around the nucleus. They have a negative charge (-).

Atomic Number

The number of _________ in the nucleus of an atom determines an element's atomic number.

So what is the Atomic Number?

6

CCarbon12.011

Atomic number.Atomic symbol

Element name

Average atomic mass -

*To find the number of protons, see the atomic number.*To find the number of electrons (see the atomic number, adjust for

charge if there is one)*To find the number of neutrons, subtract the atomic number from the atomic mass. Use whole number. Atomic mass -- 12

Atomic # - 6 6 neutrons

The number of electrons, protons, and neutrons can be changed in an atom and changes the atom!

I. Changing Electrons

An atom that changes the number of electrons is called an __________.

The number of ________ and ________ stays the same. No change in atomic number or ____________ ______________.

II. What is make an ion?

If the atom loses electrons, the atom becomes ____________ charged.

If an atom gains electrons, the atom becomes ____________ charged.

Positive ion______________

(4 +) + (3-) = 1+

Negative ion______________

(4 +) + (5-) = 1-

III. Changing Neutrons

Changing the number of neutrons in an atom makes an ________________.

Have the same _______ _____________

Have different mass numbers (number of __________ + ___________)

IV. Changing Protons

Changing the number of protons causes ________________- changing from one element to another.

The _________________and __________________ changes

Sample Problem 1: For an atom with 15 protons, 16 neutrons, and 18 electrons…

What is the atom’s net charge?

What is the atomic number of the atom? What is the mass number?

This is an atom of what element?

Sample Problem 2: For an atom with 28 protons, 31 neutrons, and 26 electrons…

What is the atom’s net charge?

What is the atomic number of the atom? What is the mass number?

This is an atom of what element?

Vocabulary

79. Democritus80. John Dalton81. Atomic theory82. J.J. Thomason83. Ernest Rutherford84. Niels Bohr85.James Chadwick86.Electron clouds87.Nucleus88.Protons89.Neutrons90.Electrons91.Atomic mass92.Atomic number93.Ion94.Isotope95.Transmutation