Physical Science Test 3

What is the charge of iron (Fe) in the compound Fe2O3?

+3

A metal can best be described as which of the following?

A network solid consisting of positively charged atoms in a sea of electrons

nuclear fission

A nuclear reaction in which a massive nucleus splits into smaller nuclei

Which of the following processes is closest to an ideal reversible process?

A pendulum swinging with almost no friction.

room temperature characteristics of ionic substances?

Brittle, non-conducting solid with high melting points.

Can sulfur be considered a compound and why?

No, it is composed of only one type of atom

Why is fusion generally considered a preferable potential energy source?

Primarily because of the difference in the waste products

When you compare saturated with unsaturated fatty acids containing the same number of carbon atoms, what is true?

Saturated fatty acids have more hydrogen atoms.

covalent bonding

a bond formed when atoms share one or more pairs of electrons. nonmetals + nonmetals. make molecules

Intamolecular forces

a force btween atoms within a single molecule. These forces are stronger than intermolecular forces. covalent bonds!

sea of electrons

a model for how the valence electrons of metal atoms are mobile and can drift from one part of a metal to another (allows for good conductivity)

a proton has a mass that is _____________ of the mass of a neutron

about the same

band gap

an energy gap that exists between the valence band and conduction band of semiconductors and insulators

H20 is a

polar molecule

an element is a substance made up of atoms that all have the same number of...

protons

beta decay

radioactive decay in which an electron is emitted, changes the element! becomes a smaller and more stable nucleus

Two types of processes

reversible and irreversible

metallic bonds conduct...

the best!

releases the most energy on a graph

the biggest decrease

Reversible process

capable of returning to initial state. ex, water or pendulum without friction

Current can flow in all directions in an LED.

false

Metals have higher ionization energies than non-metals do.

false!

intermolecular forces

forces between molecules

dipole-dipole forces

forces of attraction between polar molecules, positive attracted to negative and vice versa

set of properties is most likely those associated with methane, a covalently bonded compound?

gas at room temperature, colorless, does not conduct electricity when solid

Which of the following is NOT why alloys are useful to us today?

have a higher conductivity rate.

why use copper for wiring?

high conductor, high melting point, and malleable

ionic bonding

metals+nonmetals, move around less

Alloys

mixtures of two or more metals, bronze=copper+tin, stronger than alone metals

What classification of matter is magnesium chloride?

network matter

Which type of atom has the highest ionization energy?

nonmetals

Irreversible process

not able to be restored to initial state, the total disorder of the universe increases

alpha decay

2 protons and 2 neutrons (a helium nucleus) that is emitted during radioactive decay. changes the element!

How do semiconductors change with increasing temperatures?

When you heat them up, semiconductors act more like metals.

metals can bend and stretch because...

of the sea of electrons

metallic bond properties

1. Malleability 2. High melting point 3. opaque 4. Shiny 5. Good conductors

ionic bond properties

1. high melting point 2. non-conductive 3. brittle 4. transparent

nuclear fusion pros

1. lots of fuel 2. releases a LOT of energy 3. no radioactive material- helium is easy to find 4. the sun does this!

nuclear fission pros

1. low activation energy 2. efficient, get a lot more than we put in 3. easy chain reactions 4. what we do in a power plant

covalent bond properties

1. low melting point 2. nonconductive 3. transparent

nuclear fission cons

1. not very abundant fuel 2. radioactive material, causes cancer

nuclear fusion cons

1. requires a LOT of energy 2. not efficient, we get less than we put in

What happens to the entropy of the universe as the products are formed in an exothermic chemical reaction?

Chemical potential energy is converted into thermal energy resulting in an increase in entropy.

In order for a chemical reaction to occur

Entropy must increase as a result of the reaction

When you compare the band gap for a red and a blue LED, what is true?

The red LED has the smallest band gap.

A refrigerator is normally run with its door closed. What would happen if the refrigerator were placed in the middle of a closed room with its door open and turned on?

The room would heat up because all of the energy absorbed by the refrigerator, both thermal and electrical potential, is released back into the room as thermal energy.

What best describes how oxygen molecules would behave if mixed with water?

They would dissolve poorly or not at all because they are not polar.

Fish that swim in the cold north Atlantic would have what type of fatty acid in their blood?

Unsaturated acids with lots of double bonds.

hydrogen bonding forces

attraction of hydrogen to O, F, and N. the MOST strong

Although fusion is preferred, why are all commercial nuclear power plants using energy from fission?

because controlled fission generates large amounts of energy while current methods for controlling fusion use more energy than they produce.

Why are metals opaque?

because metals have empty, overlapping orbitals for their electrons

In which kind of radioactive decay would the number of protons in the resulting nucleus be more than in the initial nucleus?

beta decay

polar molecules need

both a positive and negative side

Which of the following is NOT a characteristic of a metal or alloy?

brittle

molecules are always...

covalent!

The force that holds molecules that do not have positive and negative sides to one another

dispersion force

3 types of forces

dispersion, dipole, hydrogen

polar molecules dissolve ________ in water

easily

semiconductors

elements that conduct an electric current under certain conditions. not quite metals or non metals, have similar properties to metals

In an irreversible process, the overall disorder of the universe...

increases

what is holding one water molecule to another water molecule?

intermolecular force

highest activation energy on a graph

is the highest energy peak

Two atoms that have the same atomic numbers but different atomic mass numbers are called

isotopes

half-life

length of time required for half of the radioactive atoms in a sample to decay

How does a catalyst affect a reaction?

lowers activation energy

How does the mass of a proton compare to the mass of an electron?

mass of the proton is much larger than the mass of an electron

metallic bonds

the force of attraction that holds metals together; it consists of the attraction of free-floating valence electrons for positively charged metal ions

When you compare the mass of the products to the mass of the reactants in a fission reaction, what do you find?

the reactants have more mass

gamma decay

the release of gamma rays from a nucleus, nothing changes. happens when there is excess energy inside of the atom

dispersion forces

the weakest of all molecular interactions, are caused by the motion of electrons, only for non polar molecules

Chemical reactions always increase the total entropy of the universe

true