Chemistry midterm

the air in the room

an example of mixture

Sand on the beach is an example of

heterogeneous mixture

Kool-Aid

homogeneous mixture

chemical property of gold

Gold is an inert (nonreactive) metal

chemical change

paper burning

70% isopropyl rubbing alcohol

Homogeneous

a pile of rusty iron filings

Heterogeneous

concrete

heterogeneous mixture

saltwater

Heterogeneous

gasoline

homogeneous mixture

bread

Heterogeneous

the law of conservation of mass follows from what concept?

atoms are indivisible

In oxides of nitrogen, such as N2O, NO, NO2, and N2O3, atoms combine in small whole-number ratios. This evidence supports the law of

Multiple proportions

According to the law of definite proportions, any two samples of KCl have what?

the same ratio of elements

Who first recognized that the ratio of the number of atoms that combine is the same as the ratio of the masses that combine?

John Dalton

Which concept in Dalton's atomic theory has been modified?

atoms cannot be divided

Dalton's theory essentially agreed with the present atomic theory EXCEPT for the statement that

all atoms of the same element have the same mass

which ancient philosopher proposed the first atomic theory?

Democritus

melting ice

A physical property may be investigated by

what is one chemical property of matter?

Reactivity

the state of matter in which a material has definite shape and definite volume

solid

the state of matter in which a material has neither a definite shape nor a definite volume

gas

silver tarnishes when it comes in contact with hydrogen sulfide in the air

chemical property

A sheet of copper can be pounded into a bowl

physical property

Barium melts at 725 degrees celsius

physical property

helium does not react with any other element

chemical property

a bar of lead is more easily bent than is a bar of aluminum of the same size

Physical property

Potassium metal is kept submerged in oil to prevent contact with oxygen or water

Chemical property

flows and takes the shape of a container

liquid and gas

compressible

gas

made of particles held in a specific arrangement

solid

has a definite volume

Liquid and solid

Always occupies the entire space of its container

gas

has a definite volume but flows

liquid

If some measurements agree closely with each other but differ widely from the actual value, these measurements are

precise, but not accurate

These values were obtained as the mass of products from the same reaction 8.83 g; 8.84 g; 8.82 g. The known mass is 8.60 g. The values are

precise

To two significant figures, the measurement 0.0255 g should be reported as

0.026 g

A sample of an element contains only one kind of

atom

Water is an example of a

compound

A solution can be distinguished from a compound by its

variable composition

a pure substance made up of more than one kind of atom is called what?

a compound

Sucrose (table sugar)

compound

the helium in a balloon

element

baking soda

compound

diamond

element

aluminum foil

element

the substances listed on the periodic table

element

calcium chloride pellets used to melt ice

compound

what is the relative mass of an electron?

1/1840 the mass of a hydrogen atom

Dalton's atomic theory included which idea?

atoms of the same element are always identical

which of the following was originally a tenet of Dalton's atomic theory, but had to be revised about a century ago?

atoms are tiny indivisible particles

Which hypothesis led to the discovery of the proton?

when a neutral hydrogen atom loses an electron, a positively-charged particle should remain

Who conducted experiments to determine the quantity of charge carried by an electron?

Millikan

which is not a part of Dalton's atomic theory?

Atoms are always in motion

How do the isotopes hydrogen-1 and hydrogen-2 differ?

hydrogen-2 has one neutron; hydrogen has none

what are all atoms (charge)

neutral, with the number of protons equaling the number of electrons

the range in size of most atomic radii is approximately how much?

5x10^-11 m to 2x10^10m

which is true about subatomic particles?

the mass of a neutron nearly equals the mass of a proton

what is correct concerning subatomic particles?

The neutron was discovered by Chadwick in 1932

Why did J.J. Thomson reason that electrons must be a part of the atoms of all elements?

charge-to-mass ratio of electrons was the same, regardless of the gas used

the comparison of the number of atoms in a copper coin the size of a penny with the number of people on Earth is meant to illustrate what?

how small atoms are

Which is the value associated with the prefix nano-?

one-billionth

which is not an appropriate unit for measuring density?

g/cm

Which value has only 4 significant digits?

6.930

how many significant digits are in the value 530,405,000

6

the SI base unit of time is?

second (s)

the SI base unit for length is?

meter (m)

the SI base unit for mass is?

kilogram (kg)

the SI derived unit for volume is?

liter

what is the ratio that compares the mass of an object to its volume?

density

what includes all known digits plus one estimated digit?

significant figures

Accuracy

how close a measurement is to the true or accepted value

Precision

how close a series of measurements are to one another

An example of a homogeneous mixture is

stainless steel

What is one difference between a mixture and a compound?

a compound can only be separated into its components by chemical means

what is true about compounds?

they are substances

what process does not involve a change in chemical property?

boiling

what is an example of physical change?

evaporation

what is an example of a homogeneous mixture?

sugar water

which is not a compound?

salad dressing

what is not a physical property of water?

it is composed of hydrogen and oxygen

what material is a substance?

Silver

Which state of matter expands when heated and is easy to compress?

gas

Oxygen has 8 electrons. How many protons does oxygen have?

8

Zinc has 30 protons. What is its atomic number?

30

Astatine has 85 protons. What is its atomic number?

85

radiation

the rays and particles that are emitted by a radioactive material

beta reaction

fast moving electrons

Nuclear Reation

A reaction that involves a change in the nucleus of an atom

radioactive decay

the process in which an unstable nucleus loses energy spontaneously

why were Democritus's ideas not science?

They were not supported by experiment

Aristotle's idea gained greater acceptance because?

he was one of the most influential philosophers of his time

what was not a feature of John Dalton's atomic research?

Discovery of the atom's internal structure

in Millikan's oil drop experiment, oil droplets are suspended in an electric field. what provides the downward force on the suspended droplets?

gravity

what is the negativity-charged particle in at atom?

electron

a proton is how much more times massive than an electron?

2000x

what is the name for atoms of an element that have different masses?

isotopes

how many protons are present in an atom potassium-39?

19

what is correct about a neutral atom?

the atom has the same number of protons and electrons

what is the charge of a beta particle?

-1