Atomic Atomic StructureStructure

Gold is an Gold is an elementelement..An An elementelement is a substance which is a substance which cannot be broken down into cannot be broken down into simpler substances under normal simpler substances under normal circumstances. circumstances.

This means that if you This means that if you break gold down into break gold down into smaller and smaller smaller and smaller pieces, it will still be pieces, it will still be gold. gold. Gold is made of Gold is made of nothing nothing

. . . but gold. . . . but gold.

Salt is Salt is notnot an an element.element.

Salt can be broken Salt can be broken down into simpler down into simpler substances--sodium substances--sodium and chlorine.and chlorine.

Gold cannot be Gold cannot be broken down into broken down into any other any other substances.substances.

The smallest, tiniest The smallest, tiniest piece of goldpiece of gold

is an is an atomatom of gold. of gold.

An atom is the smallest unit of an element.An atom is the smallest unit of an element.

The smallest particle or piece of gold The smallest particle or piece of gold is an is an atomatom of gold. of gold.

The smallest particle of The smallest particle of carbon is an carbon is an atomatom of of carbon.carbon.

Carbon is also an Carbon is also an element.element.

All atoms have 2 common structures:All atoms have 2 common structures:

nucleusnucleus

energy level(s)energy level(s)

energy levelenergy level

nucleunucleuss

electronelectronss

+ +

++

protonsprotons

neutronneutronss

--

--

Each structure is made of Each structure is made of subparticles.subparticles.

The number of protons in the nucleus The number of protons in the nucleus of an atom is that atom’s of an atom is that atom’s atomic atomic numbernumber..

Gold has 79 protons. The Gold has 79 protons. The atomic number of gold is ___.atomic number of gold is ___.

Carbon has 6 protons. The Carbon has 6 protons. The atomic number of carbon is 6.atomic number of carbon is 6. +-

---

- -

+++

++

The number of protons plus the The number of protons plus the number of neutrons in the nucleus of number of neutrons in the nucleus of an atom is its an atom is its atomic massatomic mass..

To find the number of neutrons in an To find the number of neutrons in an atom, subtract the atomic number atom, subtract the atomic number from the atomic mass.from the atomic mass.

16 Atomic mass (protons + neutrons)

- 8 Atomic number (protons)

___

8 Number of neutrons

Atomic NumberAtomic Number = =

Atomic MassAtomic Mass = =

ProtonsProtons = =

Neutrons Neutrons ==

Electrons =Electrons =

Energy LevelsEnergy Levels = =

88

1616

88

88

88

22oxygen atomoxygen atom

So far, there are over 100 So far, there are over 100 known elements. known elements. A summary of each A summary of each element’s atomic element’s atomic

structure is found in structure is found in the Periodic Table of the Periodic Table of

Elements.Elements.

more about that later . . .

NN77

nitrogennitrogen

14.00714.007

GG

element element symbolsymbol

atomic numberatomic number

state of matterstate of matter

element nameelement name

atomic massatomic mass

How many How many electrons?electrons?How many How many protons?protons?How many How many neutrons?neutrons?

777777

An example of an entry in the periodic table.

NN77

nitrogennitrogen

14.00714.007

GG The atomic The atomic mass is always mass is always rounded to the rounded to the nearest whole nearest whole number number

14.007 to 1414.007 to 14

26.560 to 2726.560 to 27