Chemistry Unit 2

Front 1

Define the term physical property and give 5 examples of physical properties of a 30 g piece of aluminum

Back 1

A physical property is a characteristic that can be readily observed without changing the substance into a new substance. Every sample of a substance has the same physical properties (density, flexibility, mass, texture, shape, odor, phase, transparency, conductivity, color, viscosity, taste, melting point)

Aluminum has the following physical properties: Silver (color), solid (state of matter), opaque (transparency), highly conductive (conductivit)y, luster, mass (30 g.), soft (flexibility)

Front 2

What is a physical change and what is the difference between a physical change and a chemical change?

Back 2

A physical change only changes some properties of a substance but the chemical composition stays the same (crushing a stone is a physical change)
In a chemical change, the composition of the matter always changes. (decomposing)

Front 3

What is the difference between an element and a compound?

Back 3

An element is a pure substance that cannot be decomposed by ordinary means to other substances, while a compound is composed or two or more elements in a fixed ratio.

Front 4

What kind of substance is air?

Back 4

homogenous mixture

Front 5

What kind of substance is Aluminum?

Back 5

element

Front 6

What kind of substance is a Chocolate chip cookie?

Back 6

heterogeneous mixture

Front 7

What kind of substance is Kool-aid?

Back 7

homogenous mixture

Front 8

What kind of substance is copper?

Back 8

element

Front 9

What kind of substance is fruit salad?

Back 9

a heterogeneous mixture

Front 10

What kind of substance is gold?

Back 10

element

Front 11

What kind of substance is milk?

Back 11

homogenous mixture

Front 12

What kind of substance is sand?

Back 12

heterogenous mixture

Front 13

What kind of substance is sea water?

Back 13

heterogenous mixture

Front 14

What kind of substance is water

Back 14

compound

Front 15

What is a chemical change? Give 4 examples that indicate a chemical reaction has taken place

Back 15

a chemical change is a reaction or change that creates a new substance "messing with the formula"

Four examples that indicate a chemical change:: heat, color change, creation of gas, and precipitation. (burn, rot, explode, decompose, rust, ferment, corrode)

Front 16

What does the law of conservation of mass explain?

Back 16

It explains that in any change or chemical reaction, mass is conserved (mass is neither created nor destroyed)

Front 17

John Dalton used experimental methods to transform DEmocritus' ideas on atoms into scientific theory. List the five results of his experiments that became Dalton's Atomic Theory.

Back 17

1. all elements are made up of atoms
2. Atoms of the same element are identical
3. different elements have different atoms;
4. compounds are made of atoms in a ratio;
(only 4 in the book)
5. mass is not made or destroyed

Front 18

What is the approximate radius of a carbon atom in meters?

Back 18

1 x 10 -9m

Front 19

What is the approximate radius of a carbon nucleus in meters?

Back 19

1 x 10 -14m

Front 20

What did JJ Thomson discover and how did he test his hypothesis?

Back 20

Thomson discovered electrons. He experimented using electric currents passing through gases sealed in tubes fitted at both ends with electrodes, which he charged with electricity. A ray developed in the tube between the negatively charged end and the positively charged end. Then he noticed how the ray was deflected, so he theorized that tiny negative electrical currents were causing the ray to repel the negative plate.

Front 21

Explain Rutherford's gold foil experiment and what he observed as a result of it

Back 21

Rutherford's gold foil experiment was to shoot alpha (large) atomic particles at a sheet of gold foil surrounded by a fluorescent screen. He noticed that the atoms mostly passed through the foil without deflection, although a few were greatly deflected.

Front 22

What did the results of the gold foil experiment lead Rutherford to theorize about the atom?

Back 22

He theorized that atoms are mostly empty space with a small "nucleus" in the center that contains all the positive charge and almost all of the mass. It is composed of protons and neutrons.

Front 23

What is the Rutherford atomic model?

Back 23

It is an atom that is made of a central nucleus with positive particles and neutral particle (protons and neutrons) concentrated in it. Electrons are distributed around the nucleus and occupy almost all of the volume of the atom (but very little of its mass).

Front 24

Diagram an atom. Identify the mass, location and charge of the protons, electrons and neutrons.

Back 24

central nucleus containing protons and neutrons, electrons in circles around it. Mass is the sum of protons and neutrons in the nucleus Neutrons are neutral, protons are positive, electrons are negative.

Front 25

Can atoms of different elements have the same atomic number? Explain your answer?

Back 25

No they cannot, because the atomic number is the number of protons in the element, and each element has a unique number of protons.

Front 26

How can you calculate the number of neutrons in the nucleus of an atom?

Back 26

By subtracting the atomic number from the atomic mass.

Front 27

What is an isotope?

Back 27

It is an element with different numbers of neutrons than the original element.

Front 28

Who is atomic mass of an atom different from the Relative Atomic Mass of an element?

Back 28

The relative atomic mass is the average of the isotopes of the element, and the atomic mass of an atom is the mass of the most prominent isotope of that atom.

Front 29

Element X has 3 isotopes; X-10 with a natural occurrence of 92.8%, X-11 with a natural occurrence of 7.1% and X-12 with a natural occurrence of 0.1%. Calculate the relative atomic mass for Element X

Back 29

(.928 x 10) + (.071 x 11) + (.001 x 12) = 9.28 + .781 + .012 = 10.073 RAM

Front 30

Explain the relationship between matter, substances, mixtures, elements , compounds, homogeneous mixtures and heterogeneous mixtures.

Back 30

Matter makes up all things. Matter is either a pure substance or a mixture. If it is a pure substance, it is made up of either atoms of the same element, or a compound, which is atoms of more than one element, all chemically combined. Matter can also combine into a mixture, which is not chemically combined. A mixture is either homogeneous, where the combination of substances is mixed evenly throughout (like milk), or heterogeneous, where the different substances in it are mixed unevenly (like sand).