Nathan Science Notes

What are 4 methods used to separate mixtures?

1. Filtration, which would involve using a filter 2. Centrifuge, which spins a mixture in order to separate the mixture 3. Distillation, which means collecting the liquid and leaving behind the heavier particles 4. Magnetism, which could be used to separate metals from nonmetals

How many atoms of Carbon is in Borax Solution: C 15 H 22 O 2?

15 atoms of carbon.

What is the maximum number of electrons that can be found in the first energy level?

2

How many atoms of Carbon is in cornstarch: C 27 H 48 O 20?

27 atoms of carbon.

Label the following as elements, compounds, or mixtures... 1. Copper wire (Cu)-element 2. Milk-mixture 3. Salt (NaCl)-compound 4. Carbon Dioxide (CO2)-compound

5. Italian Salad Dressing-mixture 6. Kool-Aid-Mixture 7. Concrete-Mixture 8. Electricity-Neither element, compound, or mixture!

What is a solubility curve?

A graph that shows how easily a solute can dissolve in a solvent at a given temperature. The red line represents how well N a N O 3, which is the salt sodium nitrate, can dissolve in water at different temperatures. The X-axis is the solvent, the Y-axis is the temperature.

A heterogeneous mixture consists of difference substances of phases that you can see with your eyes.

A heterogeneous mixture looks different throughout. Examples include sea water and concrete. A bag of M&M's would be a heterogeneous mixture. You can see red, green, blue, brown, and yellow M&M's.

A mixture can be either homogeneous or heterogeneous.

A homogeneous mixture has the same uniform composition throughout. Examples include mixtures of alcohol and water, sugar and water, and air. When you look at Kool-Aid, it all looks the same, well dissolved. Kool-Aid is a homogeneous mixture.

Which is bigger and weighs more...a proton or an electron?

A proton!

How many neutrons are in a fluorine atom?

Again, the atomic number is 9. That means it has 9 protons. If the atomic mass is basically 19, then you do the math. Atomic mass equals protons plus neutrons. If the atomic mass is 19, subtract 9 protons and you are left with 10 neutrons.

What is the difference between an atom, compound, and molecule?

An atom comes first. An atom is the smallest unit of an element. Compounds consist of two or more atoms of DIFFERENT elements. Molecules are different that compounds in that they are composed of two or more atoms, sometimes of the SAME element.

Draw an oxygen atom...

An atom of oxygen has 8 protons, 8 neutrons, and 8 electrons.

Remember this for the quiz...

An ozone molecule is O 3. It is 3 atoms of the same element, oxygen, joined together. A molecule of water is a compound, because it has H 2 0, or atoms of different elements joined together.

An unsaturated solution means that more solute could be added and it would be just fine.

An unsaturated solution is not yet saturated.

So, wait...what is the difference between atomic mass and atomic number?

Atomic mass is equal to protons plus neutrons. Atomic number is the number of protons in an atom of (in this case) carbon.

A supersaturated solution contains more solute than it can hold.

Because a solution is supersaturated, some of the solute can't dissolve.

Brass is an alloy that is 68% copper and 32% zinc. What is the solute and what is the solvent?

Because there is more copper, it is the solvent. The part of the solution that has the greatest amount will be the solvent. The least amount will be the solute.

How might you differentiate a compound from an element?

By the physical properties of the element. For example, oxygen is a gas. However, when combined with 2 atoms of hydrogen, it becomes the compound H 2 0, which is water. Water can be found in a liquid state.

So, lets look again at an atom...

Do you see the protons and the neutrons in the nucleus? Do you see the electrons in the electron cloud?

What is the area outside of the nucleus called?

Electron cloud.

How many protons, neutrons, and electrons are in boron 11?

Enlarge the picture...if the atomic number is 5, there are 5 protons and 5 electrons.

Solute is what is being dissolved in the solvent.

For example, if you are making sugar water, sugar is the solute and water is the solvent.

Concentration is the amount of solute dissolved in the solvent.

For example, the more sugar that I put in the tea, the more concentrated it is and the sweeter it is.

A pure substance is matter that has the same composition throughout.

For example, water is a pure substance. In a cup of water, there are only molecules of H 2 0.

Let's say that I made a pitcher of sweet tea, but it was TOO sweet...what can I do?

I can add more water!

If an atom gains an extra electron, is the overall charge of the atom neutral? Why or why not?

If all atoms are neutral, gaining an electron would give the atom additional negative charge.

In a direct relationship, when one goes up, the other goes up.

In an indirect relationship, when one goes up, the other goes down.

So, let's give an example of an experiment with an independent variable and a dependent variable. In this experiment, we want to see how different liquids affect plant height. Plant 1 gets orange juice, Plant 2 gets Coke, and Plant 3 gets water, then we measure the height.

In this experiment, we are changing the liquid that the plant gets, so the liquid is the independent variable. We are testing and measuring the growth or height, making height the dependent variable.

The electron cloud is outside the nucleus, and it contains the electrons.

It is made of energy levels, and each level can only hold a certain number of electrons. The 1st energy level holds 2, the 2nd energy level holds 8, and the 3rd energy level holds 18.

What is the difference between a mixture and a pure substance?

Let's begin by looking at the diagram...please enlarge it...

In the same experiment, let's say the more Coke given to the plant, the larger it grew. That means that there is a direct relationship between the amount of Coke and the growth of the plant.

Let's then say that the opposite happened when the plant got orange juice...the more orange juice the plant got, the smaller it got. That means that there is an IN direct relationship between the amount of orange juice and growth of the plant.

Isotopes are atoms that have the same number of protons, but different numbers of neutrons...

Look at the picture of the carbon isotopes. Notice how they all have the same number of protons but different numbers of neutrons.

Matter is anything that has mass and occupies space. That is its definition.

Matter can be either a pure substance or a mixture.

Is glass soluble in water?

NO!

Is sand soluble in water?

NO!

So, just to review, protons and neutrons are found together in the...

NUCLEUS of an atom! That makes the nucleus the positively charged center of the atom!

All atoms are neutral.

Neutral means they have no overall charge. This means that the number of positively charged protons must be exactly the same as the number of negatively charged electrons! If there are 4 protons, there must be 4 electrons in order for an atom to be neutral.

Which is bigger and weighs more...a proton or a neutron?

Neutrons and protons have almost the same mass!

Neutrons, like protons, are found in the nucleus.

Neutrons carry no charge.

In air, what is the solute and what is the solvent?

Nitrogen makes up the largest portion of the air that we breathe, so it is the solvent. Oxygen is present in smaller amounts, which makes it the solute.

Are the following atoms isotopes of carbon? Atom A has 6 protons, 6 neutrons, and 6 electrons Atom B has 7 protons, 7 neutrons, and 6 electrons

No, because atom B has different protons and neutrons. An isotope has the same number of protons but different numbers of neutrons.

This is a solubility curve for sugar...

Notice that as the temperature increases, the sugar dissolves better. That is why it is easier to make sweet tea with hot water rather than with cold water.

By definition, a mixture is a combination of two or more pure substances where each substance retains its own identity.

Oil and water together is a mixture...each substance retains its own identity.

Elements make up the periodic table.

On the periodic table, each box shows what 1 atom of the element is made of.

How many oxygen atoms are in a water molecule?

One molecule of water has two atoms of hydrogen and one atom of oxygen. Its chemical formula is H 2 O.

What are the subatomic particles and where are they located?

Protons and neutrons are located in the nucleus. Electrons are located in the electron cloud outside of the nucleus.

Let's look at the parts of an atom: there are protons, neutrons, and electrons.

Protons carry a positive charge. They are found in the nucleus of an atom.

So, what are the three subatomic particles?

Protons, neutrons, and electrons.

There are 3 types of solution...saturated, unsaturated, and supersaturated.

Saturated means the maximum amount of solute that can be dissolved in a solution at that temperature. We can't add any more solute or it won't dissolve.

What elements are in salt?

Sodium and chlorine. Salt has the chemical formula N a C l.

Draw a Bohr Diagram...it includes protons and neutrons in the nucleus, and electrons in the electron cloud...let's try sulfur.

Sulfur has an atomic number of 16. This means it has 16 protons and 16 electrons. Its atomic mass is 32. Atomic mass minus 16 protons equals 16 neutrons. The nucleus has 16 protons and neutrons, and the electron cloud has 16 electrons.

Remember, you must remember how many electrons can go in the first 3 levels of an electron cloud...

The 1st energy level holds 2, the 2nd energy level holds 8, and the 3rd energy level holds 18.

Now, let's revisit the atomic mass. Remember that atomic mass equals protons plus neutrons. What happens to the atomic mass on the periodic table when there are isotopes with different neutrons?

The atomic mass is the AVERAGE atomic mass of all of the isotopes of that element.

How many electrons are in a neutral phosphorus atom?

The atomic number is 15. If it is neutral, there have to be equal numbers of protons and electrons. Therefore, there must be 15 electrons.

So, let's practice...how many protons are in an oxygen atom?

The atomic number is 8. This means 8 protons and 8 electrons.

Electrons carry a negative charge and they are found outside of the nucleus in the energy levels.

The electrons are the smallest of the three parts...

Let's look at the periodic table again...

The number 6 is the atomic number, which is equal to the number of protons. C is the chemical symbol for carbon. Carbon is the chemical name. 12.0 is the atomic mass of carbon.

In salt water, what is the solute and what is the solvent?

The solute is salt, and the solvent is water.

In sweet tea (my favorite), what is the solute and what is the solvent?

The solute is sugar, and the solvent is water.

What is on the x-axis of a solubility curve?

The solvent!

What is a dependent variable?

The variable being tested and measured in a scientific experiment.

What is an independent variable?

The variable that is changed or controlled in a scientific experiment. The key to the independent variable is that it is changed or controlled in an experiment.

Everything is made of atoms...the computer, the desk, the air...

There are 95 naturally occurring kinds of atoms.

List all similarities and differences in the following isotopes... chlorine 35 and chlorine 37

They are the same element. Same atomic number and number of protons and electrons. Different numbers of neutrons, therefore, different atomic mass numbers.

So, if an atom is neutral, it has equal numbers of protons and electrons.

This means that if I know the atomic number, I know the number of protons and electrons!

List 4 components of milk...

Water, protein, fat, calcium, and phosphorus.

Let's say I go to Cracker Barrel, and I buy a cup of sweet tea. I tell the waiter that it doesn't have enough sugar. Does that mean that the concentration of sugar is strong or weak?

Weak.

How many neutrons are in a calcium atom?

Well, the atomic number is 20. That means it has 20 protons. If the atomic mass is 40, then you do the math...atomic mass equals protons plus neutrons. If the atomic mass is 40, subtract 20 protons and you are left with 20 neutrons!

Think of compounds and molecules this way...

You can have a molecule of a compound (CO2) or a molecule of an element (O2).

What method can be used to separate water into oxygen and hydrogen gas?

You can use electricity to separate the hydrogen gas from the water.

To find the atomic mass of an element, you add protons and neutrons...

atomic mass = protons + neutrons

The average atomic mass on the periodic table comes from...

averaging the masses or ALL of the naturally occurring isotopes of that element.

Atoms, therefore, the building blocks of elements...

elements are the building blocks of matter.

A chemical compound is formed when atoms of an element combine...

for example, the compound carbon dioxide is formed when one atom of carbon is combined with two atoms of oxygen...its chemical formula is c o 2. Remember that the two oxygen atoms are double bonded to the carbon atom.

What unit needs to be included to describe the mass of solute?

grams of the solute...

By definition, an atom is...

the smallest particles into which an element can be divided and still show the properties of that element.