Chemistry Mid-term Review

Three samples of 1.12g, 1.8g, and 1.562g are mixed together. The combined mass of the three samples, expressed to the correct number of sig figs would be

4.5gs

The label on a tube of toothpaste tells you it contains "the most whitening power of any tooth paste on the market" What would be the best way for you to start to evaluate this claim

Research what ingredients actually whiten teeth and see if the toothpaste contains one of those ingredients

Which of the following does not have eight valence electrons

SR+

Which of the following is an example of qualitative data: The pH of a liquid was 5, Salt crystals formed as the liquid evaporated

Salt crystals formed as the liquid evaporated

a property that depends on the extent or size of a system

extensive property

describe the properties of a liquid

low KE particles move but are still close, they move around each other

If a material can be shaped or extended by physical pressure, such as hammering which property does the material have

malleability

how mendeleev's periodic table organized

mass and chemical/ phyiscal properties

The average atomic mass of an element

may not always equal the mass of any isotopes

The idea of arranging the elements in the periodic table according to their chemical and physical properties is attributed to

mendeleev

The actual numerical charge on an electron was determined in the

millikan oil drop experiment

a student recorded the following while completing an experiment Color of substance: yellow, shiny powder Effect of magnet: yellow, shiny powder was attracted The student should classify this substance as a

mixture

The chemical formula for water, a covalent compound, is H2O The is formula is an example of

molecular formula

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

multiple proportions

a nuclear particle that has about the same mass as a proton, but with no electrical charge is called

neutron

Name the compound Ni(CIO3)2

nickel (II) chlorate

The discovery of what elements added a new column to Mendeleev's periodic table

noble gases

A bond that is less than 5% ionic is considered

nonpolar covalent

what is atomic number

number of protons on periodic table

When determining the size of an atom by measuring the distance between bonded, identical, adjacent nuclei, the radius of an atom is

one-half the distance between nuclei

multiple covalent bonds may occur in atoms that contain carbon, nitrogen, or

oxygen

Most chemical bonds are

partly ionic and partly covalent

(is this a physical or chemical change) iron melting

pc

The horizontal rows an the periodic table are called

periods

the periodic table

permits the properties of an element to be predicted before the element is discovered

A quantum of electromagnetic energy is called

photon

can be observed with out changing the identity of a substance

physical change

Iodine monochloride (ICl) has a higher boiling point than bromine (br2) partly because iodine monochloride is

polar molecule

If the atoms that shared electrons have an unequal attraction for the electrons, the bond is called

polor

A chemist obtained the values 5.2246g, 5.2353g, and 5.2501g for the mass of sample. With out knowing the true mass of the sample, it can be said that these values have

poor precision

Mendeleev left spaces in his periodic table and predicted the existence of three elements and their

properties

what is mass number

protons + neutrons

max Planck proposed that a hot object radiant energy in small, specific amounts called

quanta

A numerical result is said to have good precision it

repeated measurements agree closely

A theory is accepted as the explanation of an observed phenomenon until

repeated observations conflict with theory

Because a few alpha particles bounced back from the foil, Rutherford concluded that they were

repelled by densely pack regions of positive charge

Chemist once theroized that a molecule that contains a single bong and double bond split its time existing as one of these two structures, this effect became known

resonance

The electrons available to be lost, gained, or shared when atoms form compounds are called

valence electrons

Under ordinary conditions of temperature and pressure, the particles in a gas are

very far from one another

The only pure substance listed below is: bread dough, vinegar, vitamin C, sea water

vitamin C

what is an extensive property of matter

volume

The distance between two successive peaks on adjacent waves is its

wavelength

what happens to the frequency of a wave if the wavelength decreases

wavelength decreases frequency increaes

what is the atomic mass

weighted average of all natural occuring isotopes

what is an example of an intensive property of matter

desity

The equal but opposite charges present in the two regions of polar molecule create

dipole

all of the following are steps in the scientific method except: Observe and recording date, forming a hypothesis, discarding data inconsistent with the hypothesis, developing a model on experimental resulting

discarding data inconsistent with hyopothesis

In metallic bonds, mobile electrons surrounding the positive ions are called

electron sea

A measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound is called

electronegativity

What are two types of pure substances

element and compound

The changes of an atom from an excited state to the ground state always requires

emission of electromagnetic radiation

Using a metric ruler with 1mm divisions , the sides of a rectangular piece of plywood were measured as 3.54cm and 4.84cm, which corresponds to an area of 17.1690 cm^2. Which of these show the area expressed

17.2 cm (sig fig rules)

a single orbital in the 3d level can hold ___ electrons

2

The number of sig figs in the measurement 0.0320g is

3

When 64.4 divided by 2.00 the correct number of sig. figs in the result is

3

how many extra electrons are in the lewis structure of the phosphate ion PO4 3-

3

The product of 13cm and 5.7 is correctly reported as

74 cm

How many electrons must be shown in the Lewis structure of the hydroxide ion OH-

8

In molecule of fluorine, the two shared electrons give each fluorine atom how many electrons in the outer energy level

8

Carbon-14 (atomic number 6) the radioactive nuclide used in dating fossils has

8 neutrons

Which of the following is not an example of a molecular formula: B, O2

B

Based on the octet rule, boron will most likely form a ____ion

B3-

Bromine is much more apt to exist as an anion that is potassium This is because___

Bromine has a greater electron affinity than potassium does

What is the formula for the compounds formed by calcium ions and chloride ions

CaCl2

Dalton supported his atomic theory with experimental evidence. What experiment would have supported the postulate that in chemical reactions, atoms are combined, separated, or rearranged

Dalton observes combustion in a closed chamber, nothing that the mass is the same before and after the reaction although the products looked quite different

Which of these is not an example of a SI base unit: Kelvin, Liter

Liter

The substance whose Lewis structure shows three covalent bonds is

NH3

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

Neutrons help to make up the mass number (p plus n) and isotopes are elements with different mass numbers

Which atom has the smallest number of neutrons

Nitrogen-14 (mass number - #of protons)

You find an unknown substance that cannot be separated by filtration, evaporation, or distillation. Would the explanation that this substance is an element be scientifically valid

No, because the substance could be a compound, which also cannot be separated by physical means

(is this a physical or chemical change) pencil breaking into 2

P.C

In one experiment, magnesium metal is melted. In the second, magnesium metal is burned. Classify the change in each experiment as chemical or physical

The change is physical because the substance is still magnesium but it is just melted so the identity has not changed. In the second experiment, the change is chemical. the identity of the magnesium is gone because it is burnt

a compound is

a substance, made of two or more atoms that are chemically bonded, that can be broken down into simpler stable sunstances

Use VSEPR theory to predict the shape of carbon dioxide CO2

`linear

a chemical change occurs when

a leaf changes color in the fall

A polar molecule contains

a region of positive charge and a region of negative charge

A homogeneous mixture is also called

a solution

To appear shiny a material must be able to

absorb and re-emit light of many wavelenfths

Which of the following is an example of a homogeneous mixture: air, orange juice, raw milk, marble

air

A chemical can be defines as

any substance that has a definite composition

Moseley's work led to the realization that element with similar properties occurred at regular intervals when the element were arranged in order of increasing

atomic number

how was mosely's organized

atomic number and nuclear charge

Why do chemists work with moles instead of individual atoms

atoms are really really tiny, and avagdro's number is a really large number so a lot of atoms fit into a mole and that makes it easier to measure

Because most particles fired at metal foil passed straight through, Rutherford concluded that

atoms were mostly empty space

which of the following is not a physical change: grinding, cutting, boiling, burning

burning

how is the modern periodic table organized

by increasing atomic number

(is this a physical or chemical change) milk souring

cc

(is this a physical or chemical change) silver tarnishing

cc

The metric unit length that is closet to the diameter of a pencil is the

centimeter

the electrostatic attraction between positively charged nuclei and negatively charged electrons permits two atoms to be held together

chemical bond

changes the identity of a substance

chemical change

In the three molecules, O2, HCl and F2 what atom would have a partial negative charge

chlorine

The ions in most ionic compounds are organized into a

crystal

As atoms bond with each other

decrease their potential energy , thus creating more-stable arrangements of matter

in a row in there periodic table as the atomic number increases the atomic radius generally

decreases

The element that has the greatest electronegativity is

fluorine

a physical change occurs when a

glue gun melts a glue stick

If electrons in an atom have the lowest possible energies, the atom is in the

ground state

Compared with ionic compounds, molecular compounds

have lower melting points

In the alkaline-earth group atoms with the smallest radii

have the highest ionization energies

describe the properties of a gas

high KE particles separate and move throughout the container can fill a space but not run in to the same particle

If a mixture is uniform in composition, it is said to be

homogenous

consider the following postulates of dalton's atomic theory i. Each element is composed of extremely small particles called atoms ii. atoms are indivisible iii.atoms of a given element are identical iv. Atoms of different elements are different and have properties Which of the postulates is(are) no longer considered valid

ii. and iii.

a property that does not depend on the amount of matter present, such as pressure, temperature, or density

intensive property

how are frequency and wavelength related

inversely- can't change wavelength without changing frequency

The greater the electronegativity difference between two bonded atoms, the greater the percentage of ____ in the bond

ionic character

The energy required to remove an electron from an atom is the atom;s

ionization energy

Name the compound Fe(NO3)2

iron (II) nirate

In drawing a Lewis structure, the central atom is generally the

least electronegative atom

a state of matter in which a material has no definite shape but has a definite volume is the ____ state

liguid

Explain nuclear charge and how is affects the general trend in radii of atoms of elements going from left of right across a period in the periodic table

look on ipad

describe the properties of a soild

low K.E fixed shape and volume particles can vibrate but can't move

In groups 13 through 18, valence electrons may be in sublevel

s and p

what orbitals do electrons occupy

s and p

Compared with nonmetals, the number of valence electrons in metals is generally smaller

smaller

Use VSEPR theory to prdict the shape of the carbon tetraiodide molecule Cl4

tetrahedral

The major difference between a 1s orbital and 2s orbital is that

the 2s orbital is at a higher energy level

Cathode rays are deflected away from negatively charged plate because

the are negatively charged particles

An atom is electrically neutral because

the number of protons and electrons are equal

Which of these statements about y=kx, is not true

the product of y and x is constant

which model of atom explains the orbitals of electrons as waves

the quantum model

according to the law of definite proportions any two samples of KCl

the same ratio of elements

According to the particle model of light, certain kinds of light cannot eject electrons from metals because

the wavelength of the light is too short

A line spectrum is produced when an electron moves from one energy level

to a lower energy level

Use VSEPR theory to predict the shape of the chloride ion ClO3-

trigonal pyramidal

the noble gases were, until relatively recently thought to be entirely nonreactive. Experiments in the early 1960's showed the Xe could in fact form compounds with fluorine. The formation of compounds consisting of Xe is made possible by

xenon's relatively low ionization enegry

What is true about the y=kx

y is directly proportional to x, x is a variable, the graph of y versus x is a straight line