Biology, 7Th Grade, Chapter 4

Front 1

matter


4.1

Back 1

Anything that occupies space and has mass -- the physical "stuff" of the universe. Composed of one or more chemical elements.

Front 2

element


4.1

Back 2

A pure substance that can't be broken down into other substances by chemical means.

Front 3

trace element


4.1

Back 3

Elements that make up less than 0.01 percent of your body mass.

Front 4

compound


4.1

Back 4

Substance containing two or more lelements that are chemically combined in a fixed ratio. EG. water H20 always contains the same ratio of hydrogen combined with oxygen.

Front 5

What are the most common elements in living things.

4.1

Back 5

96% of living matter in a body is made of Calcium (Ca), phosphoros (P), potassium (K), sulfur (s)

Front 6

Compare and contrast elements and compounds.

4.1

Back 6

An element is a pure substance that can't be broken down and compounds contain one or more elements that are combined in a fixed ratio.

Front 7

What are the four most abundent elements in a human, in order of decreasing % of body mass.

4.1

Back 7

Oxygen 65%
Carbon (18.5%)
Hydrogen (9.5%)
Nitrogen (3.3%)

Front 8

Why are trace elements important in a human body?

4.1

Back 8

Even though they exist in small amounts they do vital things. Iron helps carry oxygen in blood and iodine regulates the thyroid.

Front 9

atom


4.2

Back 9

From greek atomos "indivisible" is the smallest possible "piece" of the element carbon.

Front 10

proton


4.2

Back 10

A subatomic particle with a single unit of positive electrical charge.

Front 11

electron


4.2

Back 11

A subatomic particle with a single unit of negative electrical charge.

Front 12

neutron


4.2

Back 12

A subatomic particle, is has no electrical charge (its nutral)

Front 13

nucleus


4.2

Back 13

A central core of an atom where protons and neutrons are tightly packed to form the core.

Front 14

atomic number


4.2

Back 14

The number of protons contained in an element's atroms. All atoms of a particular element have the same number of protons known as the elements atomic number. Helium with 2 protons has an atomic number of 2.

Front 15

isotope


4.2

Back 15

Elements with alternate forms. Isotopes of an element have the same number of protons in their atoms but different numbers of neutrons.

Front 16

radioactive isotope


4.2

Back 16

An isotope in which the nucleus decays (breaks down) over time, giving off radiation in the form of matter and energy.

Front 17

Describe the structure of an atom.

4.2

Back 17

An atoms structure is determined by an element's properties. The number of protons determines the properties.

Front 18

Explain how isotopes can be used to study biological processes.

4.2

Back 18

Livign cells use radioactive isotopes just like nonradioactive forms. They act as biological speis for observing what happens to diffrent atoms within an organism.

Front 19

Explain the role of an element's elctrons in determining its chemical reactivity.

4.2

Back 19

Electrons differ in the amount of energy they have and how tightly they are helpd by the protons in the nucleus. Electrons with higher energy levels determine how the atom reacts.

Front 20

Describe 3 subatomic particles and how they are arranged in an atom.

Back 20

Atoms of all elements are made up of even smaller compounds called subatomic particles. 1) proton w/1 positive charge, 2) electron w/1 negative charge and 3) neutron with no charge.

Front 21

What is the significance of electrons in an atom's highest energy level.

4.2

Back 21

Electrons in the highest energy level of an atom determine how that atom reacts.

Front 22

Explain the significance of an element's atomic number.

4.2

Back 22

All atoms of a particular element have the same number of protons "atomic number"

Front 23

ionic bond


4.3

Back 23

A chemical bond that occurs when an atom transfers an electron to another atom.

Front 24

ion


4.3

Back 24

Atoms or groups of atoms that have become electrically charged as a result of gaining or losing electrons.

Front 25

covalent bond


4.3

Back 25

Forms when two atoms share electrons.

Front 26

molecule


4.3

Back 26

Two or more atoms held together by covalent bonds form a molecule.

Front 27

chemical reaction


4.3

Back 27

When a cell's molecules rearrange into other molecules and existing chemical bonds break and form new ones. This chemical reaction forms one or more new substances.

Front 28

reactant


4.3

Back 28

The starting materials for chemical reactions.

Front 29

product


4.3

Back 29

The ending materials in chemical reactions.

Front 30

Compare and contrast ionic and covalent bonds.

4.3

Back 30

Ionic bonds happens when an atom transfers an electron to another atom. A covalent bond forms when two atoms share electrons.

Front 31

How can you represent molecules?

4.3

Back 31

By using element symbols with dots representing the atoms' outermost electrons.

Front 32

What happens in a chemical reaction?

4.3

Back 32

They rearrange atoms, usually by breaking chemical bonds in reactants and forming new bonds in products.

Front 33

How is an ionic bond formed? How is it different in a covalent bond?

4.3


4.2

Back 33

Ionic bonds form when an atom transfers an electron to another atom. Covalent bonds form when two atms share electrons.

Front 34

In C6, H12, O6+ how many atoms of each element are present.

4.3

Back 34

6, 12, and 6.

Front 35

What does a chemical formula tell you?

4.3

Back 35

The number and types of atoms in a molecule.

Front 36

What is a structural formula


4.3

Back 36

Indicates how atoms in a molecule are linked by bonds. Each line between symbols shows a single covalent bond (shaired pair of elctrons).

Front 37

What is a space-filling model?


4.3

Back 37

Color coded spheres symbolize atoms as 3-dimentional drawings.

Front 38

What is a chemical formula?


4.3

Back 38

It tells you the number and types of atoms in a molecule.

Front 39

polar molecule


4.4

Back 39

A molecule in which opposite ends have opposite electrical charged.

Front 40

hydrogen bond


4.4

Back 40

Resulting from the weak attraction between a hydrogen atom of one molecule and a slightly negative atom with another molecule creates this chemical bond.

Front 41

cohesion


4.4

Back 41

The tendancy of molecules of the same kind to stick to one another.

Front 42

adhesion


4.4

Back 42

The attraction that occurs between unlike molecules.

Front 43

thermal energy


4.4

Back 43

The total amount of energy associated with the random movement of atoms and molecules in asample of matter.

Front 44

temperature


4.4

Back 44

A measure of the average energy of random motion of the particles in a substance.

Front 45

solution


4.4

Back 45

A uniform mixture of two or more substances. Like when you stir table salt into water.

Front 46

solvent


4.4

Back 46

The substance that dissolves the other substance and is present in the greater amount. (i.e, in salt water it is water).

Front 47

solute


4.4

Back 47

The substance that is dissolved and is present in a lesser amount is the solute. (Salt in salt water).

Front 48

aqueous solution


4.4

Back 48

When water is the solvent, the result is called and aqueous solution. From latin "Aqua" water.

Front 49

acid


4.4

Back 49

A compound that denotes H+ ions to a solution is called an acid.

Front 50

base


4.4

Back 50

A compound that removed H+ ions from an aqueous solution.

Front 51

PH scale


4.4

Back 51

Describes how acidic or basic a solution is.

Front 52

buffer


4.4

Back 52

Sobstances that cause a solution to resist changes in pH. Exist because molecules in cells are very sensitive to concentrations of H+ and OH-.

Front 53

Describe the structure of a water molecule.

4.4

Back 53

Two hydrogen atoms are each moined to an oxygen atom by a single covalent bond, but the covalent bonds are not shared equallly between oxygen and hydrogen atoms.

Front 54

List and describe water's unique properties.

4.4

Back 54

Cohesion, adhesion, temperature moderation, the lower density of ice compared to liquid water and water's ability to dissolve other substances.

Front 55

Explain how Earth's conditions are fit for life.

4.4

Back 55

The abundance of water, the planets location in the solar system so it receives enough but not too much energy from the sun while ozone shields the plants upper atmospher. The availability in the soil, rock and atmosphere of the elements essential to life.

Front 56

How does the structure of water molecules result in attractions among them.

4.4

Back 56

The slightly negative oxygen end of one molecule attracts the slightly positive hydrogen ends of adjacent water molecules causing the molecues to become arranged in a week attraction.

Front 57

How is cohesion in water molecules important to living things?

4.4

Back 57

It helps keep large molecules organized and arranged in a way that enables them to function properly in cells. Trees also depend on adhesion to transport water from roots to leaves.

Front 58

What information does the pH scale provide?


4.4

Back 58

Acidity.

Front 59

How can water moderate temperature?

4.4

Back 59

It stores heat and releases it at night. Evaporation cools.