Chemistry Midterm Review

How and where did the natural elements form?

They formed in stars. Smaller stars formed smaller elements. Larger stars formed larger elements. Supernovas and massive stars form elements heavier than iron.

What elements are produced by more massive stars?

Elements heavier than iron,.

How did larger elements (beyond iron) form?

Through supernovas

What is the relationship between the life cycle of a star and its mass?

The path the star follows depends on its mass. The larger the mass, the shorter the life cycle.

What element is the building block for all other natural elements?

Hydrogen

What is the difference between chemical and physical changes?

Physical changes affect physical properties w/ no new change in chemical composition. Chemical changes is when entirely new substances form with different properties.

What are physical properties?

Physical properties are characteristics observed without changing the identity of the substance. Ex. color, density, melting points.

What are chemical properties?

A characteristic of a substance observed through a chemical reaction. Ex. flammability, heat of combustion, acidity.

What is the difference between reactants and products in chemical reactions?

A reactant is is the original substance in a chemical reaction. A product is a new substance created through a chemical reaction.

What are the particles like in solids?

The particles vibrate and are tightly packed.

What are the particles like in liquids?

The particles are lightly held together and can slip past each other.

What are the particles like in gases?

The particles are slightly held together and can move independently at higher speeds.

What is the difference between pure substances and mixtures?

Pure substances have definitive characteristics and are elements and compounds. Mixtures have properties that reflect those in pure substances. The composition can vary by proportion.

What are some methods for separating mixtures?

Filtration, magnetism, evaporation, by hand, dissolving, condensation

Which state of matter has the highest kinetic energy and why?

Gas; the particles are slightly held together, so it can move independently at higher speeds

Why does a given quantity of water heated at a constant rate take longer to change from liquid to gas than from solid to liquid?

A greater amount of potential energy is stored in the particles of a gas.

What are 4 naturally occurring diatomic elements?

Hydrogen, Nitrogen, Fluorine, Oxygen, Iodine, Chlorine, Bromine (Have No Fear Of Ice Cold Beer)

What are three forms of energy?

Kinetic energy, Potential energy, Heat energy

What is the boiling point of water on the Kelvin scale?

373 Kelvin

What is the boiling point of water on the Celsius scale?

100 degrees Celsius

What subatomic particles are found in an atom’s nucleus?

Protons and Neutrons

Where are electrons found in an atom?

In electron clouds and orbitals

What is bright line spectra?

Bright line spectra is the light emitted when electrons move between energy levels.

How can an element’s bright line spectra be used identify elements in unknown materials?

Each element has a unique line spectra.

Which has a longer wavelength, orange or violet light?

Orange Light

Which has a higher energy, x-rays or gamma rays?

Gamma Rays

Which has a lower energy, infrared light or x-rays?

Infrared Light

Do atoms release energy when electrons jump to higher energy levels?

No

What is an electron cloud?

The space around the nucleus where electrons are located.

What letter represents the principal quantum number?

n

All electromagnetic radiation can be thought of as moving ….

waves

As the frequency of a wave increases, the wavelength…

decreases

Why can protons exist so close together within the nucleus of the atom?

The strong force holds together the subatomic particles of the nucleus.

What determines the type of bond an atom can form?

The valence electrons

Why can properties of elements in the same group be predicted?

They have the same number of valence electrons so they act similarly.

Why did Mendeleev have gaps in his table?

Predicted the properties of undiscovered elements when he grouped the elements by similar properties and increasing atomic mass.

How did Mendeleev use the gaps in the periodic table?

He used it predict undiscovered elements.

What is the importance of valence electrons?

They are the only electrons that partake in chemical reaction.

How is the electron configuration similar for each element in a group?

They have the same number of valence electrons and the same ending sublevel.

Where are metals located on the periodic table?

Located to the left of the red staircase.

Where are metalloids located on the periodic table?

Metalloids are bordering the red staircase.

Where are nonmetals located on the periodic table?

Located to the right of the red staircase.

Where are noble gases located on the periodic table?

Group 18

Where are the halogens located on the periodic table?

Group 17

Where are the alkali metals located on the periodic table?

Group 1

Where are the alkaline earth metals located on the periodic table?

Group 2

Identify a group of inert elements.

Noble Gases

Which sublevel do transition elements fill?

The d sublevel

What trend in atomic radius do you see as you go down a group?

It increases due to electrons occupying additional energyy levels.

What trend in atomic radius do you see as you go across a period?

It decreases across a period because additional protons pull the electrons closer.

Ionization Energy

Energy needed to remove an electron from a neutral atom or an ion.

What trend in ionization energy do you see as you go down a group?

It decreases due to occupied energy levels and electron shielding.

What trend in ionization energy do you see as you go across a period?

Increases across a period because of additional protons pull the electrons closer.

Electronegativity

An atom’s attraction for electrons when bonded to another atom.

What trend in electronegativity do you see as you go down a group?

Decreases down groups due to additional energy levels and electron shielding.

What trend in electronegativity do you see as you go across a period?

Increases across a period due to additional protons.

What is the most reactive metal?

Francium

What is the most reactive nonmetal?

Fluorine

How do you express specific heat?

joules per gram Kelvin (J/gK)

What is the SI unit for energy?

joules (J)

What is the equation for specific heat capacity?

Cp=q/mT ( q=energy, m=mass, T=change in temp)

What units do you use for heat of fusion?

J/g

How do you calculate percent error?

( I Your Answer - Accepted Value I / Accepted Value ) times 100

Dalton's Atomic Theory

1. Matter composed of indivisible particles called atoms.
2. Each element's atoms are alike.
3. Atoms of different elements have different masses.
4. Atoms of different elements combine in whole numbers to form compounds.
5. In chemical reactions, atoms are rearranged, not created nor destroyed.

Which principles of Dalton's Atomic Theory are no longer true?

1. Matter composed of indivisible particles called atoms.
2. Each element's atoms are alike.

JJ Thomson

Experimented with cathode ray tube; Discovered electrons

Strong Force

Holds the protons and neutrons together in the nucleus of an atom. The closely packs neutrons and protons creates the strong force which is stronger than the repulsive force.

What unit is atomic mass measured in?

amu (atomic mass units); 1 amu is 1/12th the mass of one carbon atom

How do you find the atomic mass?

Add the number of protons and neutrons.

Isotope

Atoms of the same element with different number of neutrons.

Equation for Mass Number

Mass Number = protons + neutrons

Alpha Particle

A small, positively charge particle, which Rutherford directed at thin, gold foil

Anode

The electrode attached to the positive terminal of a voltage source

Cathode

The electrode attached to the negative terminal of a voltage source

Anion

Negatively charged atom with more electrons than protons

Ernest Rutherford

Experimented with gold foil; Discovered atom is mostly empty space and the nucleus contains most of the atom's mass

Which 2 subatomic particles have significant masses?

Protons & Neutrons

Cations

Positively charged particles that have lost electrons.

How can you calculate the charge of an atom?

Protons - Electrons = Charge

Equation for Average Atomic Mass

Average Atomic Mass = (mass of isotope 1 x abundance) + ( mass of isotope 2 x abundance)

Photon

When an electron releases energy in the form of light.

What is the speed of light?

2\.988 x 10^8 m/s or 3.00 x 10^8 m/s

In the equation c = λ x v, what does c represent?

Speed of Light

In the equation c = λ x v, what does λ represent?

Wavelength

In the equation c = λ x v, what does v represent?

Frequency

In the equation E = h x v, what does h represent?

Planck's Constant

In the equation E = h x v, what does e represent?

Energy

In the equation c = λ x v, are λ and v inversely or directly proportional?

Inversely

Do all wavelengths on the electromagnetic spectrum travel at the same speed?

Yes

What does quantum # n describe about an electron?

The electrons distance from the nucleus aka what energy level it's in.

What are the four sublevels in order of energy?

s,p,d,f

How many orbitals does sublevel s have?

1 orbital

How many orbitals does sublevel p have?

3 orbitals

How many orbitals does sublevel d have?

5 orbitals

How many orbitals does sublevel f have?

7 orbitals

How many electrons can each orbital hold?

2 electrons

Pauli Exclusion Principle

Within each orbital, electrons spin in opposite directions. Two electrons in one orbital can't be spinning the same way.

Aufbau Principle

Electrons fill the lowest energy levels first.

Hund's Rule

P orbital fill with one electron at a time; no pairing until each p orbital has one electron.

Electromagnetic Spectrum

All of the frequencies or wavelengths of electromagnetic radiation.