Bio- Chapter 2 Flashcards Preview

Fall 2016 > Bio- Chapter 2 > Flashcards

Flashcards in Bio- Chapter 2 Deck (42):
1

Matter

Anything that occupies space and mass

2

Mass

Is a measure of the amount of material in an object

3

Element

Is a substance that cannot be broken down into other substances by chemical reactions

4

What four elements make up 96% of the human body's weight?

Oxygen, carbon, hydrogen, and nitrogen.

5

Trace Elements

Are required in only very small amounts, but you cannot live without them.

6

Compounds

Substances that contain two or more elements in a fixed ratio.

7

Atom

The smallest unit of matter that still retains the properties of an element.

8

Protons

Is a subatomic particle with a single unit of positive electrical charge

9

Electron

Is a subatomic particle with a single negative charge

10

Neutron

Is electrically neutral

11

Nucleus

The atoms center core

12

When an atom has an equal number of protons and electrons..

its net electrical charge is zero and so the atom is neutral

13

Atomic Number

All atoms of a particular element have the same unique number of protons.

14

Mass Number

The sum of the number of protons and neutrons.

15

Atomic Mass

listed in the periodic table as the bottom number and it is close to the mass number-the sum of its protons and neutrons-but may differ slightly because it represents an average of all the naturally occurring forms of that element.

16

Isotopes

Have the same numbers of protons and electrons as a standard atom of that element but different numbers of neutrons.

17

How many of the naturally occurring elements are used by your body? Which four are the most abundant in living cells?

25, oxygen, carbon, hydrogen, and nitrogen.

18

By definition, all atoms of carbon have exactly 6____, but the number of _____ varies from one isotope to another.

Protons, neutrons

19

Radioactive Isotope

One in which the nucleus decays spontaneously, shedding particles and energy

20

Only__ are directly involved in chemical reactions.

Electrons

21

Chemical Bonds

These interactions usually result in atoms staying close together, held by attractions.

22

Ions

Atoms or molecules that are electrically charged as a result of gaining or loosing electrons

23

Ionic Bond

The attraction between oppositely charged ions

24

Covalent Bond

When two atoms share one or more pairs of electrons. Covalent bonds are the strongest.

25

Molecule

Covalent bonds hold atoms together in this

26

When lithium ion(+) joins a bromide ion(-) to form lithium bromide, the resulting bond is a___ bond.

ionic

27

Polar Molecule

Is one with an uneven distribution of charge that creates two poles, one positive pole and one negative pole.

28

Hydrogen Bonds

These are the weakest attraction

29

Chemical Reactions

Changes in chemical composition of matter.

30

Reactants and Products

Starting molecules to the end product

31

Cohesion

The tendency of molecules of the same kind to stick together.

32

Evaporative Cooling

When a substance evaporates, the surface of the liquid that remains cools down.

33

Solution

a liquid consisting of a homogeneous mixture of two or more substances.

34

Solvent

Dissolving agent

35

Solute

Any substance that is dissolved

36

Aqueous Solution

When water is the solvent, this is the resulting solution

37

Acid

A chemical compound that releases H+ to a solution

38

pH Scale

A measure of the hydrogen ion concentration in a solution.

39

Base

A compound that accepts H+ and removes them from solution.

40

Why does water not spill over the cup?

Surface tension due to waters cohesion

41

Why does ice float?

Ice is less dense than water because the more stable hydrogen bonds lock the molecules into a spacious crystal.

42

Buffers

Substances that minimize changes in pH by accepting H+ when that ion is excess and donating H+ when it is depleted.