NYS Regents Chemistry

Neutrons

No charge (Neutral)

1 atomic mass unit

found in the nucleus

Protons

Positive Charge

found in the nucleus

Electrons

Negative Charge

Found outside the nucleus

Atomic Number

The number of protons and electrons in an atom

Atomic Structure

Each atom has a Nucleus

Protons and Neutrons are found inside the Nucleus

Electrons found outside the Nucleus

Charges of Protons and Electrons

Equal but opposite charges

Protons+Neutrons=

Mass Number

Nuclide Symbol

a shorthand way to indicate the element, its atomic number and its mass number

Other ways to identify the Mass Number

cobalt-60

carbon-13

Isotopes

Have the same atomic number but different mass numbers

Nuclear Charge

the total charge of the nucleus of an element is equal to the atomic number of the element

Stability of the Isotopes

based on their ratio of neutrons to protons

Energy Levels

can hold a certain maximum number of electrons

Energy

The first level electrons have the lowest energy

Each level has more energy than the previous level

The outermost level has electrons with the most energy

Calculating Average Atomic Mass

The SUM of: the Percent abundance of each isotope/100 x mass of the isotope

Valence Electrons

the electrons in the outermost energy level (the last electrons written in the electron configuration

Electron Configuration

found on the lower left hand corner of the elements symbol

Kernel

includes all the non valence electrons

Ground State (normal electron configuration)

when the electrons are all in their lowest possible energy levels

Flame Test

when atoms of an element are put in a flame on or more electrons absorb energy and jump up to the excited state

Excited State

when one or more electrons gain energy and "jump up" to a higher energy level

Bright Line Spectrum

bands of color that can be seen when looking at the flame test through a prism

Lewis electron dot diagram

a method used to represent an element and its valence electrons

Rutheford's Gold Foil Experiment

Fired alpha particles at a thin sheet of gold foil

Most particles passed through

Some particles were deflected

Conclusion: atoms contain a small dense positively core surrounded by mostly empty space

The Wave Model of the Atom

Modern model of the atom

Orbitals known as an electron cloud

Orbital

a region of space in an atom where there is a high probability of finding an electron

Arrangement of the Periodic Table

elements on the modern periodic table are arranged in order of increasing atomic number

First Ionization Energy

the energy needed to remove an electron from an atom

Electronegativity

an atoms attraction for electrons

Melting Point

the kelvin temperature that a solid becomes a liquid

Boiling Point

the kelvin temperature that a liquid becomes a gas

Density

mass per unit volume

Atomic Radius

the size of the atom

Metals

are found on the left side of the "staircase" of the periodic table

Properties of Metals

1) Low electronegativity

2) Low Ionization Energy

3) Most metallic on lower left side of table

4) Malleable

5) Ductile

6) Good conductor of heat and electricity

Nonmetals

found on the right side of the "staircase" of the periodic table

Properties of Nonmetals

1) High electronegativity

2) High Ionization Energy

3) Most nonmetallic on upper right side of table

4) Solid nonmetals are brittle

5) Poor conductor of heat and electricity

Metalloids

the elements found along the "staircase" that have properties of both metal and nonmetal atoms

Groups

Vertical

All elements in a group have similar chemical properties and the same number of valence electrons

Properties of Noble Gases

They do not combine with any other element

Have 8 valence electrons

STP

Standard temperature and pressure

Periods

the 7 horizontal rows

elements do not have similar chemical properties

Stable Octets

all noble gases have eight valence electrons

all atoms want eight

Ions

formed when atoms gain or lose electrons

Gram Formula Mass

the sum of the elements atomic masses

Hydrates

compounds that are loosely bonded to a certain number of water molecules

Molecular Formula

actual formula

Empirical Formula

simplest ratio

Structural Formula

shows arrangement of the elements

Mole

a unit measure

One mole of a compound is equal to the GFM

Chemical Formula

the shorthand way to represent a compound

Chemical Reactions

conservation of MASS, ENERGY & CHARGE

Balancing Chemical Reactions

the total number and type of atoms on the left (reactants) must be equal to the total number and type of atom son the rights (Products)

Chemical Bonding

the "stuff" that holds atoms together

Bond Energy

Potential energy is stored in chemical ponds

When bonds are formed energy is released,the final product is more stable than the reactant

Breaking Bonds

When bonds are broken energy is absorbed, the product is less stable than the reactant

Naming Ions

when nonmetal atoms gain electrons to become negative ions the name of the element is changed

Net charge of an ion

the net charge of an ion is calculated by adding the total number of positive protons to the total number of negative electrons

Covalent/Molecular

Nonmetal-Nonmetal

Sharing electrons

Ionic

Metal-Nonmetal

Transfer of Electrons

Covalent Properties

Gases, Liquids, Soft Solids

Low Melting & Boiling Point

Nonconductor of electricity

Ionic Properties

Solid

Crystalline

High Melting & Boiling Point

Conducts Electricity

Diatomic Molecules

Two identical atoms bonded together

Polyatomic Ions

any compound that has both Ionic and Covalent bonds

Nonpolar Bonds

formed between two nonmetals with the same electronegativity, this causes equal sharing of electrons

Polar Bonds

formed between two nonmetals with different electronegativity, this causes an unequal sharing of electrons

the greater the EN difference the more polar

Polar Molecules

Asymmetrical in shape

Nonpolar Molecules

Symmetrical in shape

Like dissolves Like

Polar molecules and ionic compounds can only dissolve in other polar molecules

Nonpolar molecules can only dissolve in other nonpolar molecules

Intermolecular Forces of Attraction

forces that hold molecules together

*Polar have stronger IMF than nonpolar molecules

Electronegativity Difference and Covalent Bonds

covalent bonds are formed when the EN difference is less than 1.7

Electronegativity Difference and Ionic Bonds

ionic bonds are formed when the EN difference is greater than or equal to 1.7

Ionic Character

the greater the electronegativity difference the greater the ionic character

Metallic Bonding

Holds metal atoms together

"a positive immersed in a sea of mobile electrons"

Energy

the ability to do work

Law of Conservation

in any chemical reaction energy may change in form but the total amount of energy in the system remains constant

Forms of Energy

1) Heat

2) Chemical

3) Electrical

4) Nuclear

5) Mechanical

6) Light

Heat Energy

Thermal energy, random motion of atoms and molecules in a sample of air

Temperature

the temperature of a sample of matter is the measure of the average kinetic energy of the particles in the sample

Celsius Scale

0 degrees is the freezing point of water

100 degrees is the boiling point of water

Kelvin Scale

273 is the freezing point of water

373 is the boiling point of water

Heat Movement

always moves from areas of higher temperature to areas of lower temperature

Potential Energy

also known as stored energy, changes during phase changes

Specific Heat

the energy needed to raise the temperature of one gram of substance

Heat of Fusion

the amount of energy needed to melt or freeze one gram of a substance at its melting point without changing its temperature

Heat of Vaporization

the energy needed to boil (vaporize) or condense one gram of a substance at its boiling point without changing its temperature

Sublimation

the direct phase change from a solid to a gas

Ideal Gas Theory

All Gas Particles:

1) Are in random, constant, straight line motion

2) Are separated by great distances relative to

3) The volume of gas particles is considered negligible

4) Have litter or no attractive forces between them

5) Have collisions that may result in a transfer of energy between particles but the total energy of the system remains constant

6) Take the shape and volume of their container

7) Have no definite shape and no definite volume

Increasing the pressure on a gas

Decrease the volume of the gas

Increases the number of collisions between the ga molecules

Increases the temperature of the gas

Increasing the temperature of a gas

Increases the velocity of the gas molecules

Increases the number of collisions between gas molecules

Increases the volume of the gas

Increases the pressure of the gas

Ideal Gases

1) High temperature

2) Low Pressure

3) Smaller particles

4) Particles are far apart

5) Particles have weak attraction for each other

Real Gases

1) Low temperature

2) High Pressure

3) Larger particles

4) Particles are close together

5) Particles have a force of attraction between each other

Avogadro's Hypothesis

equal volumes of any gas, under the same conditions of the temperature and pressure, will always contain the same number of molecules

Boyle's Law

The volume of any ideal gas is inversely proportional to the pressure of the gas

As the pressure on a gas increases the volume of the gas decreases

As the pressure on a gas decreases the volume of the gas increases

If you double the pressure, the volume is halved

Charles' Law

The volume of any ideal gas is directly proportional to the kelvin temperature

As the temperature of a gas increases the volume of the gas increases

As the temperature of a gas decreases the volume of the gas decreases

Combined Gas Law

combines both Boyle's Law and Charle's Law

Vapor Pressure

the force exerted at the surface of a liquid or a solid

Temperature and Vapor Pressure

as temperature increases, vapor pressure increases

Vapor Pressure and Boiling

when vapor pressure equals air pressure, boiling will occur

Air Pressure and Boiling

if the air pressure decreases the boiling point of a liquid it will also decrease