Ch. 2 - Atomic Structure I. Subatomic Particles II. The Periodic Table

Subatomic Particles Most of the atom’s mass. NUCLEUS ELECTRONS PROTONS NEUTRONS NEGATIVE CHARGE POSITIVE CHARGE NEUTRAL CHARGE ATOM QUARKS Atomic Number equals the # of... equal in a neutral atom

Subatomic Particles (Parts of the Atom) Particle Symbol Charge Relative Mass Electron e amu Proton p amu Neutronn amu

Location of Subatomic Particles Electron (-) Nucleus Proton (+) Neutron

Atoms Family Album Click on the Light Bulb to See the Atoms Family Album

Atoms are building blocks of elements. Each element is made of only one type of atom. Example: Aluminum is made only of aluminum atoms.

Each element’s atoms are different from atoms of other elements. Example: Aluminum’s atoms are different from copper’s atoms.

Atomic Number The number of protons in the atom. (If the atom is neutral, it is also the number of electrons.)

Atomic Number on the Periodic Table 6C6C Symbol Atomic Number

All atoms of an element have the same number of protons! 6C6C Carbon 6 protons

Learning Check State the number of protons (or electrons) for atoms of each of the following: 1. Nitrogen A) 5 B) 7 C) Sulfur A) 32 B) 16 C) 6 3. Barium A) 137 B) 81 C) 56

Mass Number Counts the number of protons plus neutrons in an atom, so to find the number of neutrons you simply use this formula: Mass # - Atomic # = # of neutrons

Atomic Symbols Show the mass number and atomic number Give the symbol of the element 6 C 12 Mass Number Atomic Number

Number of Electrons An atom is neutral The net charge is zero Number of protons = Number of electrons Atomic number = Number of electrons

Subatomic Particles in Some Atoms O P Zn p + 15 p + 30 p + 8 e - 15 e - 30 e - 8 n16 n35 n

Drawing Atomic Models  The first electron shell/level/cloud can hold 2 electrons  The second electron shell/level/cloud can hold 8 electrons  The third electron shell/level/cloud can hold 18 electrons  The neutrons and protons are in the nucleus (center)

Let’s draw a model for sodium (Na)  How many protons does it have? 6 (same as atomic number)  How many neutrons? 6 (atomic mass - atomic number = = 6)  How many electrons? 6 (same as # of protons) C 6 12

Where do we put this stuff?  6 protons, 6 neutrons, 6 electrons  Protons and neutrons go in the nucleus  Electrons go in the orbitals/shells/clouds

e-e- e-e- e-e- e-e- e-e- e-e- 6 p + 6 n 0 Protons and neutrons go in the nucleus How many electrons fit in the first shell? How many electrons fit in the second shell? How many electrons fit in the third shell?

Examples of 3-d Bohr Models  Visionlearning Visionlearning

The Elements Song

Lewis Dot Structure C

What does this symbol mean? Carbon Dots tell you valence electrons C

Valence Electrons? C Valence electrons are electrons in the outermost shell of an atom. They are involved in forming bonds with other elements.

How do you figure out valence electrons? C 12 6 Protons? 6 (same as atomic number) Neutrons? 6 (atomic mass - atomic number) Electrons? 6 (same as atomic number)

So we know carbon has 6 electrons…now what? 6p+ 6n e- How many are in the outermost shell? The first shell holds 2. Now 4 are left. They go in the second shell. 4!

4 valence electrons=4 dots! C

How to draw your dots… Cl Chlorine has 7 valence electrons. First put dots on each side before you double up.

An Easy Trick! (1)5(1)4 (1)8 (1)7(1)62(1)31 Exception! To figure out how many dots to draw

If an element has a full outermost shell, that means it does not react with anything. Ne Which elements have full outermost shells?

Now you try… 1.Lithium 2.Nitrogen 3.Calcium 4.Oxygen 5.Fluorine N Li Ca O F