Discovering Design with Chemistry Ch. 2

a substance whose properties are the same throughout

pure substance

a combination of two or more substances

mixture

a mixture whose composition is the same throughout the sample

homogeneous mixture

a mixture whose composition is different in different parts of the sample

heterogeneous mixture

in any chemical or physical process, the total mass of everything involved must remain the same

Law of Mass Conservation

a substance that cannot be chemically broken down into simpler substances

element

a pure substance that is composed of two or more elements

compound

a given compound will always have the same proportion of elements by mass

Law of Definite Proportions

a combination of two or more atoms joined together

molecule

when two elements combine to form different compounds, a fixed amount of one element will combine with the other element so that the ratio of the masses of the other element is a small whole number

Law of Multiple Proportions

two or more atoms of the same element that have different numbers of neutrons

isotopes

heterogeneous mixture

classify the following as an element, compound, heterogeneous mixture, or homogeneous mixture:

a bowl of fruit and yogurt

element

classify the following as an element, compound, heterogeneous mixture, or homogeneous mixture:

a sample of helium gas (which cannot be broken down into simpler substances)

(the picture is not of just helium gas; it's of balloons containing helium gas)

homogeneous mixture

classify the following as an element, compound, heterogeneous mixture, or homogeneous mixture:

sugar dissolved in water

compound

classify the following as an element, compound, heterogeneous mixture, or homogeneous mixture:

sodium bicarbonate/baking soda (which can be broken down into hydrogen, carbon, oxygen, and sodium)

element

classify the following as an element, compound, heterogeneous mixture, or homogeneous mixture:

magnesium (one of the simplest substances produced when magnesium oxide breaks down)

compound

classify the following as an element, compound, heterogeneous mixture, or homogeneous mixture:

magnesium oxide (which is made of other substances, including magnesium)

heterogeneous mixture

classify the following as an element, compound, heterogeneous mixture, or homogeneous mixture:

a strawberry

homogeneous mixture

classify the following as an element, compound, heterogeneous mixture, or homogeneous mixture:

a cup of tea with no leaves in it

no, because the Law of Mass Conservation says the mass cannot change

If a student does a chemical reaction with two chemicals, the total mass of which is 45.0 g, but only collects 34.5 g of chemicals at the end, has he collected all the products of the reaction? Why or why not?

10.5 g

If a student does a chemical reaction with two chemicals, the total mass of which is 45.0 g, but only collects 34.5 g of chemicals at the end, what is the mass of the chemical(s) the student didn't collect?

In a mixture, the substances retain their own properties, but in a compound, they lose their individual properties to make the properties of the compound.

Water is a compound that can be broken down into hydrogen gas and oxygen gas. However, a mixture of hydrogen gas and oxygen gas looks and behaves nothing like water. Why?

30.1 g

If a 75.0 g sample of a white powder is chemically broken down into 29.86 g of copper, 15.06 g of sulfur, and an unknown amount of oxygen, how much oxygen gas was made?

4.45 g of copper, 2.24 g of sulfur, 4.48 g of oxygen

A 75.0 g sample of a white powder is created with 29.86 g of copper, 15.06 g of sulfur, and 30.1 g of oxygen. How much copper, sulfur, and oxygen would you need to create 11.2 g of this powder?

91.58 g of manganese, 53.34 g of oxygen

To make 86.94 g of a black powder, you need 54.94 g of manganese and 32.00 g of oxygen. How much manganese and oxygen do you need to create 144.9 g of this powder?

1. All matter is made up of atoms, which are indestructible and indivisible.

2. All atoms of a given element are identical in all their properties.

3. Compounds are formed by a combination of two or more different kinds of atoms.

4. A chemical reaction is a rearrangement of the atoms that exist in the substances which are reacting.

Dalton's Atomic Theory (original)

1. All matter is made up of atoms.

2. All atoms of a given element are identical in their chemical properties.

3. Compounds are formed by a combination of two or more different kinds of atoms.

4. A chemical reaction is a rearrangement of the atoms that exist in the substances which are reacting.

Dalton's Atomic Theory (edited)

4

A chemist makes two different compounds from the same two elements (tin and chlorine). He reacts 50.0 g of tin with 29.87 g of chlorine and, with nothing left over, creates a compound that has two atoms of chlorine per molecule. His second compound has 50.0 g of tin and 59.74 g of chlorine (also no leftovers). How many atoms of chlorine are in a molecule of the second compound?

22.84 g

A chemist makes a compound from nitrogen and oxygen with 10.0 g of nitrogen and 11.42 g of oxygen to make 21.42 g of a gas. To make a gas, starting with 10.0 g of nitrogen, and having no leftover, should he choose 20.50, 22.84, or 32.12 of oxygen?

protons, neutrons, electrons

What three particles make up most atoms?

positive charge (+)

What charge do protons have?

no charge

What charge do neutrons have?

negative charge (-)

What charge do electrons have?

the positive charge is spread throughout the atom like a pudding and the electrons are embedded in the pudding, like plums

Describe the plum pudding model of the atom.

Rutherford('s)

Whose experiment proved the plum pudding model of the atom wrong?

the positive charge is concentrated in the center of the atom, and the electrons orbit the charge like the planets orbit the sun

Describe the planetary model of the atom.

neutron

What particle doesn't appear in some hydrogen atoms?

Rutherford

Who proposed the planetary model of the atom?

oxygen

When you burn a fuel, what besides the fuel gets used up?

protons, neutrons

What particles do you find in the nucleus of an atom?