Introduction to Chemistry

Unit D Chapter 1.1NCSCOS 4.01 and 4.02

Basic Chemistry• Everything around you is made up of

either MATTER or ENERGY.

• MATTER is anything with mass and volume, no matter the size.

• The periodic table is a summary of all ELEMENTS in the universe, which make up MATTER.

• An ELEMENT is the most basic kind of matter and CAN NOT be broken down into simpler substances. ELEMENTS are pure.

Periodic Table of ELEMENTS• The current Periodic Table has 118 Elements -

92 occur naturally, the other 26 are SYNTHETIC elements = man-made.

All Matter is made of ATOMS• Atoms are tiny particles that

make up matter; atoms are the smallest form of elements; atoms of 1 type= own element (“basic…pure”)

• Ex: All the atoms of gold are identical & all the atoms of silver are identical, but the atoms of gold are very different from silver.

• Atoms are made up of even smaller particles!

Did YOU Know?????

• It would take YOU about 500 years to count the # of atoms in a grain of salt! ….o my!

•contains millions of atoms!

Most Common Elements• Universe = Hydrogen (about 90% of total

mass of Universe)• Humans = Carbon, Hydrogen, Oxygen,

Nitrogen• Humans are 61-65% Oxygen!

•“CHON”

Atomic Structure3 Subatomic Particles:

1. PROTONS: POSITIVELY charged particles (p+)

2. NEUTRONS: Uncharged or NEUTRAL particles /NO charge

3. ELECTRONS:

NEGATIVELY charged particles (e-)

*PROTONS and NEUTRONS are always found together in the NUCLEUS

*ELECTRONS will always orbit around the nucleus in the ELECTRON CLOUD (TVs, computers…images created by moving electron beam)

Overall charge of nucleus = +

Overall charge of electron cloud = ---

***Opposite charges attract & Like charges repel!!***

Atomic Structure

Elements are identified• by : Atomic Number-

the # of PROTONS in an atom (ex: H - 1)

• All elements have a different Atomic Number (unique!), Atomic Number never changes!

• Atomic Mass Number- = # of protons and neutrons in an atom

• The nucleus holds the MASS!

IsotopesISOTOPES: atoms of the same

element with a different # of NEUTRONS.

To find ATOMIC MASS # OF ISOTOPES:

Add PROTONS + NEUTRONSEX: Chlorine atoms – 17

protons

However..some Cl atoms have 18 neutrons; some have 20 neutrons

Interpret a Square on the Periodic Table

• Elements go in order based on Atomic Number (= # of protons)

• Symbol & Name• Atomic Mass = protons +

neutrons, decimal because it is average of all isotopes of element

• Electrons = same # as Protons (if neutral atom!)

• To find # of neutrons: SUBTRACT Atomic # from Atomic Mass # (rounded)

When Atoms have….EQUAL # of ELECTRONS & PROTONS ( e = - ; p = + ) SO….NO overall electrical charge!!!

When Atoms have…DIFFERENT # of ELECTRONS & PROTONS form an ION

so…DOES have an overall electrical charge

IONS are formed when ATOMS GAIN or LOSE

ELECTRONS!!