L3 Electrons and Chemical Bonding (plus Physical/Chemical Changes)

Atom

The smallest particle into which an element can be divided and still be the same element.

Electrons

Negatively charged particles that are located in the cloud around the nucleus of an atom.

Electron Cloud

The area around the nucleus where the electrons are located; does NOT show the exact number or location of electrons.

Periodic Table

Mendeleev's arrangement of the elements; still in use by chemists today.

Group (or family)

A vertical (top to bottom) of elements on the periodic table.

Valence Electrons

Electrons found in the outermost energy level of an atom.

Chemical Bond

An interaction that holds atoms or ions together.

Reactants

The elements or compounds that enter into a chemical reaction; listed on the left side of the arrow in a chemical equation.

Products

The elements or compounds produced by a chemical reaction; listed on the right side of the arrow in a chemical equation.

Bohr Model

Model of an atom that shows electrons in circular orbits around the nucleus; number of electrons IS shown.

Space-filling Molecular Model

Representation of a molecule that uses solid spheres to represent atoms and show the 3D arrangement of atoms in a molecule.

# of valence electrons group 1 elements contain

1

# of valence electrons group 2 elements contain

2

# of valence electrons group 15 elements contain

5

# of valence electrons group 18 elements contain

8

The 6 most abundant elements in the human body

Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorous, and Sulfur (C,H,N,O,P,S)

Trace Elements

Elements required by humans, but in only very small quantities

maximum # valence electrons in an atom's first shell

2

maximum # valence electrons in an atom's second shell

8

Physical Change

A change that alters the form or appearance of a material but does not make the material into another substance.

Chemical Change

A change that occurs when one or more substances change into entirely new substances with different properties.

Law of Conservation of Mass

The law that states that mass cannot be created or destroyed in ordinary chemical and physical changes.

Signs of a chemical change

Production of a new gas, Color change, Heat or Light is given off, Odor change, Solid Precipitate forms

Precipitate

A solid that forms from a solution during a chemical reaction.

Three ways an atom can form a chemical bond

Give, Take, or Share Valence Electrons

Covalent Bond

A chemical bond formed when two atoms share electrons

Ionic Bond

Formed when one or more electrons are transferred from one atom to another