Understanding Matter: Elements, Atoms, and Chemical Bonds, Study notes of Biology

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The Chemistry of Life

The Chemistry of Life

John Kaminski

John Kaminski

BIO 140: General Biology

BIO 140: General Biology

Delaware Tech - Wilmington

Delaware Tech - Wilmington

What is Chemistry?

What is Chemistry?



Chemistry is the study of the nature of

Chemistry is the study of the nature of

matter.

matter.

What is an element?

What is an element?



An element is a pure substance that

An element is a pure substance that

cannot be broken down into simpler

cannot be broken down into simpler

components by ordinary chemical

components by ordinary chemical

processes.

processes.



Common elements in living things include

Common elements in living things include

C, H, N, O, P, and S.

C, H, N, O, P, and S.

What is an atom?

What is an atom?



An atom is the smallest particle into which

An atom is the smallest particle into which

an element may be divided and still retain

an element may be divided and still retain

its chemical properties.

its chemical properties.



An atom consists of

An atom consists of



A nucleus, which contains

A nucleus, which contains



Protons

Protons



Neutrons

Neutrons



A cloud of electrons

A cloud of electrons

Charges

Charges



Electrons have a negative charge. The

Electrons have a negative charge. The

charge of an individual electron is said to

charge of an individual electron is said to

be (-1).

be (-1).



Protons have a positive charge. The

Protons have a positive charge. The

charge of an individual proton is said to be

charge of an individual proton is said to be



Neutrons have no electrical charge.

Neutrons have no electrical charge.

Neutral Atoms

Neutral Atoms



An atom with equal numbers of protons

An atom with equal numbers of protons

and electrons has an overall charge of

and electrons has an overall charge of

zero, and is called a

zero, and is called a neutral atom

neutral atom .



As an example, a neutral carbon atom

As an example, a neutral carbon atom

contains 6 protons and 6 electrons.

contains 6 protons and 6 electrons.

(+6)+(-6) = 0

(+6)+(-6) = 0

Atomic Number

Atomic Number



Atomic number is the number of protons in

Atomic number is the number of protons in

an atom.

an atom.



Each element consists of atoms with a

Each element consists of atoms with a

specific atomic number.

specific atomic number.



Carbon atoms, for instance, always contain 6

Carbon atoms, for instance, always contain 6

protons and are therefore always given the

protons and are therefore always given the

atomic number 6.

atomic number 6.

Isotopes

Isotopes



Isotopes

Isotopes are two or more atoms with

are two or more atoms with

equal numbers of protons (and, therefore,

equal numbers of protons (and, therefore,

identical atomic numbers) but with

identical atomic numbers) but with

different numbers of neutrons.

different numbers of neutrons.



In other words, isotopes are two or more

In other words, isotopes are two or more

atoms of the same element with different

atoms of the same element with different

numbers of neutrons.

numbers of neutrons.

What is a Molecule?

What is a Molecule?



A molecule is a group of two or more

A molecule is a group of two or more

atoms held together by energy.

atoms held together by energy.



The energy that holds the atoms together

The energy that holds the atoms together

in a molecule acts like glue or like an

in a molecule acts like glue or like an

attractive force, and is called a

attractive force, and is called a

chemical

chemical

bond

bond .

Three Types of Chemical Bonds

Three Types of Chemical Bonds



Ionic Bond

Ionic Bond



Covalent Bond

Covalent Bond



Hydrogen Bond

Hydrogen Bond

Covalent Bond

Covalent Bond



A covalent bond is a chemical bond that forms

A covalent bond is a chemical bond that forms

between two atoms when those atoms share

between two atoms when those atoms share

electrons.

electrons.



This type of bond forms because some atoms

This type of bond forms because some atoms

need to gain or lose electrons to be more stable.

need to gain or lose electrons to be more stable.

In a way, such atoms are more "comfortable" if

In a way, such atoms are more "comfortable" if

they share electrons with other atoms with

they share electrons with other atoms with

similar needs.

similar needs.



Covalent bonds are the strongest type of

Covalent bonds are the strongest type of

chemical bonds.

chemical bonds.



Example: water.

Example: water.

Hydrogen Bond

Hydrogen Bond



A hydrogen bond

A hydrogen bond is a very weak type of bond

is a very weak type of bond

that occurs between some molecules that

that occurs between some molecules that

contain covalent bonds. Such molecules are

contain covalent bonds. Such molecules are

said to be

said to be

polar

polar

, which means that they have an

, which means that they have an

uneven distribution of shared electrons.

uneven distribution of shared electrons.



A hydrogen bond is formed when the positive

A hydrogen bond is formed when the positive

region of one polar molecule is attracted to the

region of one polar molecule is attracted to the

negative region of another polar molecule.

negative region of another polar molecule.

Organic Molecules

Organic Molecules



Definition – molecules that contain carbon

Definition – molecules that contain carbon

(C) and usually contain hydrogen (H)

(C) and usually contain hydrogen (H)



Large organic molecules are often called

Large organic molecules are often called

organic macromolecules

organic macromolecules .

Main Classes of Organic

Main Classes of Organic

Macromolecules

Macromolecules



Carbohydrates

Carbohydrates



Lipids

Lipids



Proteins

Proteins



Nucleic Acids

Nucleic Acids