2.1 – Atoms, Ions, and Molecules

Do Now:

In terms of chemistry, what do a frog, a skyscraper, and your body all have in common?

Atoms

Atom- smallest basic unit of matter

It would take more than 1 trillion years to count the atoms in a single grain of sand

H

O

Hydrogen atom (H)

Oxygen atom (O)

Subatomic Particles

Atoms are made up of 3 smaller parts:

1. Protons (+) – Found in nucleus

2. Neutrons (0) – Found in nucleus

3. Electrons (-) – Energy levels outside of nucleus

Oxygen atom (O)

Nucleus:8 protons (+)8 neutrons

outermost energy level: 6 electrons (-)

inner energy level: 2 electrons (-)

Elements

Element- one particular type of atom, cannot be broken down

If all elements are made up of atoms… what distinguishes between elements?

Reading the periodic table:

Elements in living things

“CHNOPS”

Carbon, Hydrogen, Oxyen, and Nitrogen make up about 95% of our body

Sulfur is needed for proteinsPhosphorous is needed for DNAYou must memorize these!!!!!

Compound

Compound- a substance made of atoms of different elements bonded together in a certain ratio

A compound has different properties than the elements that it is made of

What type of chemical compounds have we talked about so far this year?

OHH

_

++

Carbon Dioxide

Example:

Hydrogen and Oxygen are both found as gases naturally on earth

BUT… when combined they can form water

A diamond is pure carbon but carbon atoms are also found in sugar, protein, and millions of other compounds.

Quick review:

How are elements different from compounds?

Give at least 2 reasons:

Ions form when atoms gain or lose electrons.

An ion is an atom that has gained or lost one or more electrons. positive ions

negative ions

• Ionic bonds form between oppositely charged ions. They are held together by electrical force!

• Easily dissolve in water!

Sodium atom (Na) Chlorine atom (CI) Sodium ion (Na+) Chloride ion (CI-)

Na loses anelectron to CI ionic bond

gained electron

Ionic Bond Example:

How do we know if an atom wants to gain or lose electrons?

The atom wants a full energy level by moving the LEAST amount of electrons So…

If it has 3 or less electrons it will give electrons away and become POSITIVELY charged

If it has 5 or more electrons it will gain more electrons and become NEGATIVELY charged

Atoms share pairs of electrons in covalent bonds.

A covalent bond forms when atoms share a pair of electrons.

Usually very strong! covalent bonds

Oxygen atom (O) Carbon atom (C) Oxygen atom (O)

Carbon dioxide (CO2 )

– multiple covalent bonds– diatomic molecules

– Ex: O2

Molecules

Molecule- two or more atoms held together by covalent bonds

One last type of bonding – Dipole-Dipole

Due to the unequal sharing of electrons, some molecules have a slightly positive and a slightly negative end to them, or a dipole (di-pole = two magnetic poles)

These compounds can form weak bonds with one another without combining together completely to create new compounds

Ex: Water hydrogen bonds Van Der Waals forces

Isotopes

Isotope: An atom that contains a larger or smaller number of neutrons than usual

-similar chemical properties

-still no charge

Student ntoes

2.1 – Atoms, Ions, and Molecules

Atoms

Atom- ______________________________

It would take more than 1 trillion years to count the atoms in a single grain of sand

H

O

______________ Particles

Atoms are made up of 3 smaller parts:

1. _____________(+) – Found in ______________

2. ____________(0) – Found in _______________

3. ______________(-) – Energy levels outside of nucleus

Oxygen atom (O)

Nucleus:8 protons (+)8 neutrons

outermost energy level: 6 electrons (-)

inner energy level: 2 electrons (-)

____________________

Element- one ____________________________, cannot be broken down

If all elements are made up of atoms… what distinguishes between elements?

Reading the periodic table:

Elements in living things

“___________________”

____________, ______________, ___________, and ____________make up about 95% of our body

Sulfur is needed for proteinsPhosphorous is needed for DNAYou must memorize these!!!!!

__________________

Compound- a substance made of ________________________________________________________________________

A compound has _______________________than the elements that it is made of

What type of chemical compounds have we talked about so far this year?

OHH

_

++

Example:

Hydrogen and Oxygen are both found as gases naturally on earth

BUT… when combined they can form water

A diamond is pure carbon but carbon atoms are also found in sugar, protein, and millions of other compounds.

Quick review:

How are elements different from compounds?

Give at least 2 reasons:

Ions form when atoms _____________________________

An _________________is an atom that has gained or lost one or more electrons. _______________ions

________________ions

• ______________________form between oppositely charged ions. They are held together by electrical force!

• ______________________________!

Sodium atom (Na) Chlorine atom (CI) Sodium ion (Na+) Chloride ion (CI-)

Na loses anelectron to CI ionic bond

gained electron

Ionic Bond Example:

How do we know if an atom wants to gain or lose electrons?

The atom wants _______________________ by moving the ___________amount of electrons

So… If it has 3 or less electrons it will give electrons away and become POSITIVELY charged

If it has 5 or more electrons it will gain more electrons and become NEGATIVELY charged

Atoms share pairs of electrons in covalent bonds.

A ________________________ forms when atoms share a pair of electrons.

Usually __________________! covalent bonds

Oxygen atom (O) Carbon atom (C) Oxygen atom (O)

Carbon dioxide (CO2 )

– multiple covalent bonds– diatomic molecules

– Ex: O2

Molecules

__________________- two or more atoms held together by _____________________