The chemical context of life

Key concepts

– Matter consists of chemical elements in pure form and in combinations called compounds

– An element’s properties depend on the structure of its atoms

– The formation and function of molecules depend on chemical bonding between atoms

– Chemical reactions make and break chemical bonds

Matter consists of chemical elements in pure form and

combinations called compounds

Matter consists of chemical elements in pure form and

combinations called compounds

What is matter?

Matter consists of chemical elements in pure form and

combinations called compounds

• Something that has mass and occupies space• Matter consists of atoms

Matter consists of chemical elements in pure form and

combinations called compounds

• Something that has mass and occupies space• Matter consists of atoms

What are atoms?

Matter consists of chemical elements in pure form and

combinations called compounds

• Something that has mass and occupies space• Matter consists of atoms

•Atoms are the fundamental building block of all substances. •The smallest unit of matter that retains the properties of an element

Matter consists of chemical elements in pure form and

combinations called compounds

• Something that has mass and occupies space• Matter consists of atoms

•Atoms are the fundamental building block of all substances. •The smallest unit of matter that retains the properties of an element.

What is an element?

Matter consists of chemical elements in pure form and

combinations called compounds

• Something that has mass and occupies space• Matter consists of atoms

•Atoms are the fundamental building block of all substances. •The smallest unit of matter that retains the properties of an element.

An element is a substance that cannot be broken down into other substances by chemical reaction.

Matter consists of chemical elements in pure form and

combinations called compounds

• Something that has mass and occupies space• Matter consists of atoms

•Atoms are the fundamental building block of all substances. •The smallest unit of matter that retains the properties of an element.

An element is a substance that cannot be broken down into other substances by chemical reaction.

Why?

Matter consists of chemical elements in pure form and

combinations called compounds

Each element is composed on a single type of atom

Compounds are made of more than one element in a fixed ratio

goldhydrogen and oxygen

sodium and chloride

Matter consists of chemical elements in pure form and

combinations called compounds

Whether they are in compounds or in pure form, there are relatively few elements in living organisms

Matter consists of chemical elements in pure form and

combinations called compounds

An element’s properties depend on the structure of its atoms

An element’s properties depend on the structure of its atoms

What do we mean by properties?

An element’s properties depend on the structure of its atoms

Properties-melting point, bonding, and density are common examples.

An element’s properties depend on the structure of its atoms

Atomic structure

Nucleus

Electron cloud

An element’s properties depend on the structure of its atoms

Atomic structure

NucleusContains:•Protons •Neutrons

Electron cloudContains:•Electrons

An element’s properties depend on the structure of its atoms

Atomic structure

NucleusContains:•Protons •Neutrons

Electron cloudContains:•Electrons

•All atoms of the same element will have the same number of protons (Atomic number)

He2

An element’s properties depend on the structure of its atoms

Atomic structure

NucleusContains:•Protons •Neutrons

Electron cloudContains:•Electrons

•All atoms of the same element will have the same number of protons (Atomic number)•The number of neutrons typically equals the number of protons

He2

An element’s properties depend on the structure of its atoms

Atomic structure

NucleusContains:•Protons •Neutrons

Electron cloudContains:•Electrons

•All atoms of the same element will have the same number of protons (Atomic number)•The number of neutrons typically equals the number of protons •Mass number is the number of protons + number of neutrons

He2

4

An element’s properties depend on the structure of its atoms

Atomic structure

NucleusContains:•Protons •Neutrons

Electron cloudContains:•Electrons

•All atoms of the same element will have the same number of protons (Atomic number)•The number of neutrons typically equals the number of protons •Mass number is the number of protons + number of neutrons•The number of electrons typically equals the number of protons

He2

4

What is the atomic number of Aluminum?

How many protons does Lithium have?

What is the mass number of Chloride?

An element’s properties depend on the structure of its atoms

Atomic structure

NucleusContains:•Protons •Neutrons

Electron cloudContains:•Electrons

•All atoms of the same element will have the same number of protons (Atomic number)•The number of neutrons typically equals the number of protons (not for isotopes)•Mass number is the number of protons + number of neutrons•The number of electrons typically equals the number of protons

He2

3

An element’s properties depend on the structure of its atoms

Atomic structure

NucleusContains:•Protons •Neutrons

Electron cloudContains:•Electrons

•All atoms of the same element will have the same number of protons (Atomic number)•The number of neutrons typically equals the number of protons (not for isotopes)•Mass number is the number of protons + number of neutrons•The number of electrons typically equals the number of protons (not for ions)

He2

4 +

An element’s properties depend on the structure of its atoms

Focusing on electrons- Atomic nuclei don’t interact, electrons do

Atomic structure

Electrons vary in the amount of energy they possess because of their position relative to the nucleus.•They are attracted to the nucleus•It takes work (energy) to be far from it•They reside in energy levels (shells)

An element’s properties depend on the structure of its atoms

Focusing on electrons- Atomic nuclei don’t interact, electrons do

Atomic structure

An element’s properties depend on the structure of its atoms

Focusing on electrons-The chemical behavior of an atom is determined by the distribution of its electrons

Atomic structure

Hydrogen

1H

Lithium

3LiBeryllium

4BeBoron

5BCarbon

6CNitrogen

7NOxygen

8O

Fluorine

9FNeon

10Ne

Helium

2He

Firstshell

Secondshell

Thirdshell

Sodium

11NaMagnesium

12Mg

Aluminum

13AlSilicon

14SiPhosphorus

15PSulfur

16S

Chlorine

17ClArgon

18Ar

An element’s properties depend on the structure of its atoms

The formation and function of molecules depend on chemical

bonding between atoms

The formation and function of molecules depend on chemical

bonding between atomsDifferent types of bonds•Covalent bonds (strongest) - involves the sharing of electrons (i.e. H2)

•Electrons may be spread equally across the bond (non-polar bond)•Electrons may not be spread equally across the bond (polar bond)

The formation and function of molecules depend on chemical

bonding between atoms

Naturalendorphin

EndorphinreceptorsBrain cell

Binding to endorphin receptors

Morphine

(b)

The formation and function of molecules depend on chemical

bonding between atomsDifferent types of bonds•Covalent bonds (strongest) - involves the sharing of electrons (i.e. H2)

•Electrons may be spread equally across the bond (non-polar bond)•Electrons may not be spread equally across the bond (polar bond)

•Ionic bonds- Charge-charge interactions•An interaction between a positive and negative charge•Can form after one atoms strips a valence electron from another (ie. NaCl)•Forms salts

The formation and function of molecules depend on chemical

bonding between atoms

Ionic bond

Electrontransferforms ions

NaSodium atom

ClChlorine atom

Na+

Sodium ion(a cation)

Cl–

Chloride ion(an anion)

Which elements will most likely form an ionic bond?

a. Li and F

b. C and O

c. N and O

d. Si and Cl

e. H and H

The formation and function of molecules depend on chemical

bonding between atomsDifferent types of bonds (weak)

•Hydrogen bonds- involve polar covalent bonds, form when a hydrogen atom is bonded to a more electronegative atom

The formation and function of molecules depend on chemical

bonding between atomsDifferent types of bonds (weak)

•Hydrogen bonds- involve polar covalent bonds, form when a hydrogen atom is bonded to a more electronegative atom

This impacts the properties of water!

The formation and function of molecules depend on chemical

bonding between atomsDifferent types of bonds (weak)

•Hydrogen bonds- involve polar covalent bonds, form when a hydrogen atom is bonded to a more electronegative atom•Vander Waals interactions- involve non-polar covalent bonds, occur when an electron accumulation arises by chance

The formation and function of molecules depend on chemical

bonding between atoms

Chemical reactions make and break chemical bonds

Chemical reactions make and break chemical bonds

Chemical reaction- making a breaking of chemical bonds leading to changes in the composition of matter

Chemical reactions make and break chemical bonds

Chemical reaction- making a breaking of chemical bonds leading to changes in the composition of matter

6 CO2 + 6 H2O C6H12O6 + 6O2

Chemical reactions make and break chemical bonds

Key concepts

– Matter consists of chemical elements in pure form and in combinations called compounds

– An element’s properties depend on the structure of its atoms

– The formation and function of molecules depend on chemical bonding between atoms

– Chemical reactions make and break chemical bonds