ATOMIC STRUCTURE

What is an atom?

The atom is the basic unit of matter. Ultimately all classes of matter can be identified or classified based on the type or types of atom that it contains.

The atom is the smallest, undividable particle of matter

What is matter?Matter is any substance which:

1. Occupies space (i.e. has volume)

2. Has mass

Is air matter? Does it occupy space? Does it have mass!

YES!

Types of Matter

Matter can be classified as a:a. Pure substance- a material having one

kind of atom or molecule ie. Oxygen (O2), or pure water (H2O)

b. Mixture- has two or more kinds of particles. ie. Salt water

Matter Map

What makes up an atom?Atoms are made of three types of subatomic particle

1. Protons (p+)- a positively charged particle located in the nucleus

2. Neutron (n0)- a neutral (uncharged) particle located in the nucleus

3. Electron (e-)- a negatively charged particle located outside the nucleus

Name Symbol Charge Location Mass

Proton p 1+ nucleus 1836Neutron n 0 nucleus 1836

Electron e 1– area surrounding the nucleus 1

Nucleus

Atomic #

Atomic mass

Go to your periodic table and find Carbon!!! Can you figure out what do all these numbers mean????

Work in pairs and share with the class!!

Atomic #

Purple Protons

Electric Electrons

Nutty Neutrons

Atomic Number

The atomic number represents the number of protons in the nucleus of the element. In the neutral atom it also represents the number of electrons.

What ‘s the atomic number for oxygen? How many electrons and protons does it have?

Which atom has 15 protons?

Let’s take a closer look at Lithium…

Atomic # is 3 Atomic # is the # of

protons in the nucleus (also the # of electrons in an atom)

So there are 3 protons , and 3 electrons

LiLithium

3

6.9

Mass NumberThe mass number represents the number of particles (neutrons and protons) in the nucleus of a specific atom; it is given this name because almost all of the mass of an atom comes from the protons and neutrons.

If an atom of nitrogen has a mass number of 14 it has 7 protons and 7 neutrons in its nucleus.

So to find the # of neutrons – we subtract the Atomic # from the atomic mass.

Atomic #

Atomic Mass

Let’s take a closer look at Lithium…

Mass # is 6.9 Mass # = the # of

Protons and neutrons together (weight of the nucleus)

# protons and neutrons together is 7 = Atomic mass

LiLithium

3

6.9

So how do we find neutrons?

LiLithium

3

6.9

How many Neutrons in Helium?

Examples of Isotopes Carbon has 3 isotopes. This is normal Carbon – C12 6 protons, 6 electrons, 6 neutrons Another isotope of Carbon is C13 C13 – 6 p, 6 e, 7 neutrons The other isotope is C14. C14 – 6 p, 6 e, 8 neutrons

CCarbon

6

12.001

CCarbon

6

13.001

CCarbon

6

14.001

Practice:Let’s try and fill in the table using the elemental symbols given! (Find # of P+, n, and e-)

# of Protons 3 9 8 56

# of Neutrons(mass number- atomic number)

4 10 8 80

# of electrons 3 9 8 56