Chemistry. Matter Matter = something that has mass and takes up space (has volume)

Chemistry

Matter

Matter = something that has mass and takes up space (has volume)

Matter

Solid

Liquid

Gas

comes in 3 main phases (plasma is outside our scope)

Solid

Definite Shape

Definite Volume

Liquid

Indefinite Shape – takes the shape of the container

Definite Volume

Gas

Indefinite Shape – takes the shape of the container

Indefinite Volume – can expand and be compressed

Elements one of the 100+ pure substances

that make up everything in the universe

Examples of Elements

H = Hydrogen

C = Carbon

O = Oxygen

N = Nitrogen

S = Sulfur

Na = Sodium

Ca = Calcium

K = Potassium

I = Iodine

Cl = Chlorine

P = Phosphorus

Atom the smallest particle considered an element

Sub-atomic Particles

Protons p+ - positive

charge, in nucleus

Electrons - e- negative charge, orbiting

nucleus

Neutrons n0 – no

charge, in nucleus

Composition of Matter

The protons and neutrons are found at the center of the atom and are located in the nucleus.

Atomic number: number of protons in the nucleus

Atomic mass: number of protons + neutrons in the nucleus

Composition of Matter

Atomic number = 1 Atomic number = 2

Atomic mass = 1 Atomic mass = 4

Drawing an Atom of Carbon

C12.011

6

Atomic Mass

Atomic #

minus Atomic # = # of n0

= # of p+ and # of e-

Carbon has 6 p+ and 6 e-

Carbon has 6 n0

Drawing an Atom of Carbon

6 p+

6 n0

e-

e-

e- e-

e-

e-

Inert (Stable) Elements

• Have complete valence shells and are stable

• Octet Rule– Outer shell must be full

for atom to be stable– Shell 1 has 2

electrons– Shell 2 has 8 electrons

• 10 = 2 + 8– Shell 3 has 8 electrons

• 18 = 2 + 8 + 8

Figure 2.4a

Isotopes

• Isotopes: atom of the same element that has a different number of neutrons

• Identified by the mass number– Carbon-12, carbon-13, and carbon-14

• Radioactive isotopes: their nuclei are unstable and break down at constant rate over time.

Compounds

Compounds - 2 or more elements chemically

combined to form a new substance with

new properties Properties – The way a

chemical substance looks and behaves

Compounds

Compounds – are made of 2 or more different atoms

combined to form Molecules

H + O H2O =

H

O

H

Chemical formula lists the number of different atoms

in a single molecule

Structural formula shows the arrangement of the

atoms in a single molecule

Molecules

Glucose Sugar

C6H12O6

Chemical formula

C

H

OH

C C

C

C CH

HH

H

H

HOH

O

OH

HOOH

Structural formula

Compounds

Inorganic

Compounds orOrganic

Compounds • usually don’t contain

Carbon

• generally come from the earth

• generally simple molecules

• always contain C & H and usually O, N, sometimes S & P

• originate in organisms

• generally complex molecules

Examples of Inorganic

Compounds

H + O = H2O = Water

H + Cl = HCl = Hydrochloric Acid

C + O = CO2 = Carbon Dioxide

Na + Cl = NaCl = Common Table Salt

Examples of Organic

Compounds

C, H + O Carbohydrates = Sugars, starches & cellulose

C, H + O Lipids = Fats & Oils

C, H, O, N, & sometimes P + S

Proteins

C, H, O, N, + P Nucleic Acids – DNA & RNA

Interactions of Matter• Chemical bonds:

1. bond atoms to form compounds,

2. are formed according to the number of electrons in the outermost energy level, and

3. will not form when an atom has a full outer energy level

Interactions of Matter• To achieve stability, an atom will

gain, lose, or share electrons.

Interactions of Matter• Ionic bonds: formed by transfer of

electrons

–Ion: charged atom; Ions form when ionic bonds occur.

Ionic bonding-- electrons are transferred

sodium (Na)

chlorine (Cl)

Ionic bonding in sodium chloride (NaCl)

Interactions of Matter• Covalent bond: formed by sharing

of electrons• Co:together, valent: valence• involve outermost energy level only• very strong

Covalent bonding-- electrons are shared

Covalent bonding

Intermolecular Forces

• van der Waals Forces– Attraction charge

between the molecules

Summary:

Quiz

1. What is a atom?

2. What are the 3 subatomic particles in an atom?

3. What does the atomic number indicate?

4. If an atom has an atomic number of 35, how many electrons does it have?

5. How many electrons are on the first shell?

6. What type of bond shares electrons?

7. What type of bond gains or loses electrons?

Quiz-Answers

1. The smallest particle of an element or basic unit of matter

2. Proton, neutron, and electron

3. Number of protons

4. 35

5. 2

6. Covalent Bond

7. Ionic Bond

Interactions of Matter

• Chemical reaction: any process in which a chemical change occurs–If energy is released →

spontaneous–If energy is required → will NOT

occur without adding energy

Interactions of Matter• Reaction formulas: represent chemical

reactions; the arrow means “react to form”

–Example: O2 + 2H2 → 2H2O

• Catalyst: a chemical that speeds a reaction up to 10,000,000,000 times faster