CHEMISTRY MIDTERM REVIEW SHEET

how many moles of platinum are equivalent to 1.20x10²⁴ atoms? (atoms to moles= atoms / 6.02 x 10²³)

1.99 x 10 moles

determine the number of moles of helium in 10.0 g of helium. the molar mass of helium is 4.00 g/mol

2.5moles

the electron configuration for nitrogen is 1s2 2s2 2p3. what does the ³ in 2p³ mean

3 valence electrons in p orbital of second level

the mass of 1 mol of gold atoms is 196.97 g. find the mass of 1 atom of gold.

3.27 x 10⁻²² ( 1/6.02x10²³=0.1661129x10⁻²³x196.97)

how many atoms are present in 8.00 mol of chlorine atoms? (moles to atoms = moles x 6.02 x 10²³)

4.816 *10²⁴ atoms

determine the mass in grams of 10.0 mol of bromine. the molar mass of bromine is 79.90 g/mol

799 grams

a team of scientists is working to discover how an enzyme affects blood cells in sheep. they are working in the field of ________ chemistry.

biochemistry

which element has the following electron configuration: [Ar] 4s² 3d¹⁰ 4p⁵?

bromine

what is an isotope?

atoms with the same number of protons but different number of neutrons

basic research is performed to increase ____________

knowledge

a scientist is working to develop better dating methods for substances that contain carbon. He is working in the field of ____________ chemistry.

organic

a scietist is working to determine the properties and changes of matter and their relation to energ of a newly discovered mineral. She is working in the field of _____________ chemistry

physical

the melting of butter is a _______ change because it does not produce any new substances.

physical

when examining a mineral, hardness and color are two of the properties used for identification. hardness and color are examples of ________ properties.

physical

distinguish between precision and accuracy

precision- exactness of a measurement accuracy- how close a measurement is to the true value

applied research is often performed to find the answer to a particular_____________

problem

distinguish between mass and weight

Mass- measure of the amount of matter Weight- measure of gravitational force on an object

write the electron configuration for nitrogen, atomic number 7

N 7 -->1s² 2s² 2p³

write the noble gas electron configuration for silicon

[Ne] 3s² 3p²

Iron and sulfur, when heated, form an iron sulfide that has different properties from either iron or sulfur. The formation of iron sulfide is an example of a ________ change.

chemical

an apple turning brown after being cut is an example of a ______ change.

chemical

Describe the law of definite proportions

chemical compound always contains the same elements in exactly the same proportions, regardless the size or source of sample.

the study of matter and changes that occur in matter best describes the science of

chemistry

some iron and sulfur are mixed together, then heated. when the result is cooled, the iron can no longer be separated from the sulfur with a magnet. the result of heating the mixture was the formation of a _______

compound

the two types of matter that are pure substances are _______ and ________

compounds and elements

matter that has neither a definite volume nor a definite shape is in the _______ state

gaseous

Gravel is an example of a ______ mixture

heterogeneous

explain the difference between a pure substance and a homogeneous mixture. give examples in your answer.

homogeneous mix can be separated by physical means a pure substance can not. you can remove salt from salt water by boiling it.

An alloy such as a gold ring is an example of a(n) ____________________ mixture.

homogenous

a chemistry student is studying the formation of quartz crystals. she is studying ____________ chemistry.

inorganic

A sample of matter can be poured from container to container. It takes the shape of its container but only takes up a certain volume. Based on this information, the sample is in the ____________________ state.

liquid

the particles of a substance in teh _________ are able to slide past each other.

liquid state

what is the relationship between isotopes, mass number, and neutrons?

mass # of is basically given by finding average of the most abundant isotope, also within mass # if # is altered by another isotope of element

Identify as metal, nonmetal, or metalloid and give two physical properties for the element Sr.

metal, malleable, good, conductor

Identify as metal, nonmetal, or metalloid and give two physical properties for the element I.

nonmetal, brittle, poor conductor of heat and electricity

what is the atomic number of an atom?

number of protons an atom has in its nucleus

in a bonfire, oxygen allows wood to combust, leaving behind ashes. in this process,oxygen and wood are the reactants, and ashes are the __________

products

explain the differences between qualitative and quantitative observations.

qualitative- descriptive (5 senses) quantitative- numerical info

technological development is performed to better our__________

quality of life

the oxygen in air causes iron to rust. iron and oxygen are ______ in this process, and rust is the product.

reactants

any substance with a definite composition is a _________

solid

a scientist is using mathematical models to isolate a new chemical process. he is working in the field of ______________ chemistry.

theoretical

two scientists are trying to determine the exact nature of the chemicals in a lava flow. they are working the field of ___________ chemistry.

thermo

what is the mass number of an atom?

total # of neutrons and protons in the nucleus

What is the law of multiple proportions?

when two elements combine with each other to form more than one compound, the mass of one element that combine with a fixed mass of the other are in a ratio of small whole numbers.