Middle School Chemistry Nov. 14, 2011

Middle School Chemistry Nov. 14, 2011

Chemical Bonding

Atoms are made up of three basic particles: positively charged ______, negatively-charged ______, and ______, which have no charge. Protons and neutrons clump together in the center of an atom, forming its ______. Electrons whizz around the nucleus at different levels, which we call ______. Each shell can hold a certain number of electrons. The first shell, closest to the nucleus, can hold ______. In general, all the shells outside of that can hold [at least]______.

Well, when an atom’s outermost shell is completely full, the atom is said to be ______; in other words, it generally won’t ______with other atoms. But when its outermost shell isn’t full, an atom is ______. It’ll try to react with other atoms or molecules, so it can have a full outer shell.

For instance, water: It’s made of two hydrogen atoms and one oxygen atom. Oxygen shares a pair of electrons with ______. This sharing of electron pairs is called a ______bond.

Ionic bonds happen when one atom takes an______from another. The extra electron gives the first atom a negative charge. And the other atom becomes positively charged, since it lost an electron. They both become ______– atoms with electrical charges. Since opposite charges attract, they bond together! This is called electrostatic attraction.

Ionic and covalent bonds can change an atom’s ______.

Bohr Model and Lewis Structure.

There are simple ways to draw the electron field of an atom.

The Bohr Model shows all the energy levels and electrons.

Chemical Bonding page 2

The 2 types of bonding we are studying are covalent and ionic (electrostatic)

Compare the two:

CovalentIonic (Electrostatic)

CoVALENT – two atoms sharing valence IONic – each atom must be an ion so their

electrons so they both have full valence shells. differences in charges attracts them to

Their sharing keeps them together. each other. (electrostatic force)

Sharing of electronsatoms take or give electrons

No ions are formedions are formed

Occurs because the atoms both want to Occurs across different sides of the

gain electrons. (in higher numbered groups)periodic table.

Usually occurs when two nonmetals bond Usually occurs between metal and

together. non metals

Draw the Lewis Structure for the first 20 elements.