Chapter 2 Flashcards Preview

Campbell Biology 10ed > Chapter 2 > Flashcards

Flashcards in Chapter 2 Deck (43):
1

Matter

Anything that has mass and takes up space

2

Element (92 naturally occurring elements)

A substance that cannot be broken down to other substances by chemical reactions. (92 naturally occurring elements)

3

Compound

A substance consisting of two or more different elements combined in a fixed ratio

4

Essential elements (20 - 25% of elements)

Elements that an organism needs to live a healthy life and reproduce. Humans require 25 elements

5

Trace elements

Elements required by an organism in only minute quantities. Iron (all forms of life) Iodine (thyroid gland)

6

96% of living matter

Just four elements—oxygen (O), carbon (C), hydrogen
(H), and nitrogen (N). COHN

7

Subatomic particles

Neutrons (neutral), protons (positive) and electrons (negative)

8

Atomic nucleus

The dense (positively charged) core at the center of an atom that contains neutrons and protons.

9

Dalton

A unit of mass a.k.a as amu (atomic mass unit). Protons and neutrons have masses close to 1 dalton. The mass of an electron is 1/2000 of a dalton.

10

Atomic number

The number of protons in an atom of a specific element. All atoms of a particular element have the same number of protons in their nuclei. Subscript to the left

11

Mass number

The sum of protons plus neutrons in the nucleus of an atom. Superscript to the left

12

Atomic mass

The total mass of an atom, close to its mass number (weighted average)

13

Isotopes

Different atoms of the same element that have different number of neutrons

14

Radioactive isotope

An isotope in which the nucleus decays spontaneously, giving off particles and energy which can transform the atom to an atom of a different element

15

Radioactive tracer

Radioactive isotopes that are incorporated into biologically active molecules, which are then used as tracers to track atoms during metabolism, the chemical processes of an organism

16

Half-life

The time it takes for 50% of the parent isotope to decay into its daughter isotope

17

Radiometric dating

Technique used to date materials by measuring the ratio of different isotopes present in the sample

18

Energy

The capacity to do work

19

Potential energy

The energy that matter possesses because of its location or structure

20

Valence electrons

The electrons in the outermost electron shell

21

Valence shell

The outermost electron shell

22

Noble gases

Gases that have completed valence shells. They are chemically inert

23

Electron shell

An orbit of electrons with a particular energy level and average distance from the nucleus

24

Chemical bond

An attraction between atoms that binds them together

25

Covalent bond

The sharing of a pair of valence electrons by two atoms

26

Molecule

Two or more atoms held together by covalent bonds

27

Single bond

One pair of shared electrons

28

Double bond

Two pairs of shared electrons

29

Valence

The bonding capacity of an atom which usually equals the number of unpaired electrons required to complete the valence shell

30

Electronegativity

The attraction of a particular atom for the electrons of a covalent bond

31

Polar covalent bond

A covalent bond whose electrons are not shared equally between the atoms giving each atom a partial charge

32

Ion

A charged atom or molecule that has gained or lost an electron

33

Cation

A positively charged atom or molecule

34

Anion

A negatively charged atom or molecule

35

Salt

Ionic compound. Compound formed by ionic bonds

36

Ionic bond

The attraction between two oppositely charged ions. An ionic bond can form when one atom transfers an electron to another atom

37

Weak bonds

Ionic bonds between ions dissociated in water, hydrogen bonds and van der Waals bonds. Weak bonds reinforce the three dimensional shape of large molecules (proteins)

38

Hydrogen bond

The attraction between an hydrogen atom and an electronegative atom

39

Van der Waals interactions

The charges that result in an atom by the random accumulation of electrons in one region

40

Chemical reaction

Involves the forming or breaking of a chemical bond

41

Reactant

A starting material in a chemical reaction

42

Product

The product of a chemical reaction

43

Chemical equilibrium

The forward and reverse reactions occur at the same rate. It is a dynamic equilibrium