BELL-RINGER QUESTION1. Look at the periodic table of elements….

How are the elements in the periodic table like the alphabet of letters?

• Review elements and bonding

(In order to prepare for comparing the structure and function of bio-molecules)

Today’s Objective:

Can be found in the book: Pg. 141 - 147

• An atom is the smallest particle of an element that has the characteristics of that element.

• Atoms are the basic building blocks of all matter.

ATOMS

• All nuclei contain positively charged particles called protons (p+).

• The center of an atom is called the nucleus.

• Most contain particles that have no charge, called neutrons (n0).

ATOMS

• In the electron cloud there are extremely small, negatively charged particles called electrons (e-)

• There is a region of space that surrounds the nucleus called the electron cloud.

• Electrons exist around the nucleus in regions known as energy levels.

• The first energy level holds 2 electrons.

• The second level holds up 8 electrons.

• The third level can hold up to 18 electrons.

• To know the number of electrons in an energy level can hold after that, use this formula, 2n²

Nucleus8 protons (p+)8 neutrons (n0)

Oxygen atom

ATOMS

• The electrons that are in the outer most energy level for that atom are called valence electrons.

ATOMS

PRACTICE MAKING ATOMS

• Everything – whether it is a rock, frog, or flower (abiotic or biotic) – is made of substances called

elements.

ELEMENTS

• An element is a pure substance made only of one kind of atom. (it cannot be broken down into a simpler chemical substance)

• Elements differ in the number of protons– Ex: Carbon has 6 protons : Hydrogen has 1 proton

ELEMENTS

5

B

10.81

Atomic Number

Atomic Symbol

Atomic Mass

PERIODIC TABLE

Atomic Number:The number of protons in an atom defines what element it is.  For example carbon atoms have six protons, hydrogen atoms have one, and oxygen atoms have eight.  The number of protons in an atom is referred to as the atomic number of that element. Atomic Symbol:The atomic symbol is one or two letters chosen to represent an element ("H" for "hydrogen," etc.).  These symbols are used internationally.  Atomic Mass:The atomic mass is the sum of protons and neutrons.

• Of all the naturally occurring elements on Earth, only about 25 are essential to living organisms.

• Carbon, hydrogen, oxygen, and nitrogen make up more that 96 percent of the mass of a human body.

ELEMENTS

Chemical Bonding

Atoms can join together during chemical bonding to form

compounds

– A Compound is a substance made of the joined atoms of two or more different elements

– Compounds are represented by a chemical formula that shows the proportions of each element in the compound

Covalent bonds

• Covalent bonds occur when two or more atoms share electrons

(co = together, valence= outer electrons)

A compound made with covalent bonds is

called a molecule

Hydrogen bonds

– Molecules with an uneven distribution of electrical charge like water have poles and have a polar attraction

– Hydrogen bonds are a weak chemical attraction between polar molecules

Water molecules are attracted to each other by hydrogen bonds

Ionic bonds• An ion is an atom that

has gained or lost an electron.

– Ions have a charge due to the unequal number of protons and electrons

• The attractive force between two ions of opposite charge is known as an ionic bond.

• Chemical reactions occur when bonds are formed or broken, causing substances to recombine into

different substances.

CHEMICAL REACTIONS

• All of the chemical reactions that occur within an organism are referred to as that organism’s

metabolism.

CHEMICAL REACTIONS

• In a chemical reaction, substances that undergo chemical reactions, are called reactants.

• Substances formed by chemical reactions, are called products.

CHEMICAL REACTIONS

In this reaction, what are the reactants and what is the product?

Question 1Which of the following is an element?

D. water

C. sodium chloride

B. carbon

A. chlorophyll

The answer is B.

An element can't be broken down into simpler chemical substances. Chemical elements combine in different ways to form a variety of substances useful to living things.

Answer

The smallest particle of an element that has the characteristics of that element is a(n) __________.

Question 2

D. atom

C. nucleus

B. electron

A. proton

The answer is D. Atoms are the basic building blocks of all matter and have the same general structure, including a nucleus and electrons. Elements found in both living and nonliving things are made of atoms.

Nucleus

Electron energy levels

An atom has a nucleus and electrons in energy levels.

Answer

Which of the following can contain two types of particles?

D. electrons

Question 3

B. protons

C. neutrons

A. nucleus

The answer is A. The nucleus is the center of the atom and may contain both positively charged particles and particles that have no charge.

Nucleus8 protons (p+)8 neutrons (n0)

Oxygen atom

Answer