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Biology > Chemical Context of Life (Unit 1) > Flashcards

Chemical Context of Life (Unit 1) Flashcards

1
Q

Organisms are composed of —–

A

Matter

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2
Q

Matter is

A

anything that takes up space and has mass

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3
Q

Element

A

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

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4
Q

Compound

A

a substance consisting of two or more elements in a fixed ratio
- characteristics different from those of its elements

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5
Q

4 elements that make up 96% of life

A

Carbon, hydrogen, oxygen, and nitrogen

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6
Q

Trace elements

A

required by an organism in only minute quantities

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7
Q

Examples of trace elements

A

4% consists of calcium, phosphorus, potassium, and sulfur

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8
Q

3 subatomic particles

A

Neutrons (no electrical charge)
Protons (positive charge)
Electrons (negative charge)

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9
Q

What particles form the atomic nucleus?

A

Neutrons and protons

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10
Q

Relation of neutron mass and proton mass

A

measured in daltons and equal to each other

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11
Q

Atomic number

A

number of protons in its nucleus

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12
Q

Elemental Mass Number

A

sum of protons plus neutrons in the nucleus

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13
Q

Atomic Mass

A

the atom’s total mass, can be approximated by the mass number

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14
Q

Atoms in Element *Number of Protons and Neutrons

A

Proton- Same in all atoms of element
Neutron- can be different

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15
Q

Isotopes

A

two atoms of an element that differ in number of neutrons

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16
Q

Radioactive isotopes

A

decay spontaneously, giving off particles and energy

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17
Q

What gives elements their property?

A

Protons

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18
Q

Radioactive isotopes are often used for?

A

diagnostic tools in medicine

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19
Q

Radioactive tracers

A

can be used to track atoms through metabolism

20
Q

Radiometric Dating

A

scientists measure the ratio of different isotopes and calculate how many half-lives have passed since the fossil or rock was formed

21
Q

Half-Life

A

A “parent” isotope decays into its “daughter” isotope at a fixed rate, expressed as the half-life
They can vary from seconds o days.

Other Definition: The half-life of a reaction is the time required for the reactant concentration to decrease to one-half its initial value.

22
Q

Valence electrons

A

are those in the outermost shell, or valence shell

23
Q

Valence Electrons determine

A

chemical behavior of an atom

24
Q

What does having a full valence shell mean?

A

The atom is chemically inert

25
Q

Orbital

A

three-dimensional space where an electron is found 90% of the time

26
Q

Chemical Bonds

A

Atoms with incomplete valence shells can share or transfer valence electrons with certain other atoms

These interactions usually result in atoms staying close together, held by attractions called
chemical bonds

27
Q

Covalent Bond

A
  • The sharing of a pair of valence electrons by two atoms

-In a covalent bond, the shared electrons count as part of each atom’s valence shell

28
Q

Molecule

A

consists of two or more atoms held together by covalent bonds

29
Q

Double Bond vs Single Bond

A
  • A single covalent bond, or single bond, is the sharing of one pair of valence electrons
  • A double covalent bond, or double bond, is the sharing of two pairs of valence electrons
30
Q

Electronegativity

A

an atom’s attraction for the electrons in a covalent bond

31
Q

The more electronegative an atom is, the …….

A

The more electronegative an atom is, the more strongly it pulls shared electrons toward itself

32
Q

nonpolar covalent bond

A

the atoms share the electron equally

33
Q

polar covalent bond

A

one atom is more electronegative

the atoms do not share
the electron equally

34
Q

ION

A

A charged atom (or molecule) is called an ion

35
Q

Disassociate

A

when ion is placed in water

36
Q

Cation

A

A cation is a positively charged ion

37
Q

Anion

A

An anion is a negatively charged ion

38
Q

ionic bond

A

An ionic bond is an attraction between an anion and a cation

39
Q

ionic compounds/ salts

A

Compounds formed by ionic bonds are called ionic compounds, or salts

40
Q

Strongest bonds

A

Covalent Bonds

41
Q

Hydrogen Bond

A

bond forms when a hydrogen atom covalently bonded to one electronegative atom

42
Q

Van der Waals interactions

A

are attractions between molecules that are close together as a result of electrons that are not evenly distributed, they may accumulate by chance in one part of a molecule

43
Q

A molecule’s — and —– are key to its function

A

A molecule’s size and shape are key to its function

44
Q

A molecule’s shape is determined by the

A

A molecule’s shape is determined by the positions of its atoms’ orbitals

45
Q
A
46
Q
A

Biology (20 decks)

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