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Flashcards in Biology: Chemistry Of Life Part 1 Deck (42):
1

Elements 4

1. Pure substances
2. Basic raw material of living things
3. Each element contains one type of atom
4. More than 90 natural elements on earth

2

Scientists have created artificial elements

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3

Organisms consist of mostly four elements what are they

1. Oxygen
2. Carbon
3. Nitrogen
4. Hydrogen

4

Atom

1. Smallest unit that has properties of a given element
2. Tiny in size
3. Made of subatomic particles
4. Include protons, neutrons, and electrons

5

All atoms consist of one or more 3

1. Protons
2. Neutrons
3. Electrons

6

Protons 2

1. Carry a positive charge
2. Marked by a plus sign

7

Neutrons

Carry no charge

8

Electrons 2

1. Negative charge
2. Marked by a minus

9

Atoms usually have an equal number of protons and electrons

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10

Atomic number of an element

The number of protons in the nucleus

11

Mass number of an element

Sum of the number of protons and neutrons in the nucleus

12

Isotopes 4

1. Varying form of an atom
2. Same number of protons
3. Different number of neutrons
4. Can be more or less

13

Most elements have at least two isotopes

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14

Isotopes behave the same as the standard form in chemical reactions

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15

Radioisotopes 3

1. Isotopes of certain elements such as uranium
2. Radioactivity
3. Important uses in medicine

16

Radioactivity 3

1. Emission of energy and certain types of particles to stabilize the nucleus of a radioisotope
2. Happens at a predictable rate
3. Basis of dating very old substances

17

Positron emission tomography

Technology using radioisotopes to detect tumors

18

Tracer

Molecule in which radioisotopes have been substituted for some atoms

19

Cells in a cancerous tumor take up tracer faster than surrounding cells

Therefore scanner can detect concentrated radioactivity

20

Atoms interact through their electrons 2

1. May share, give up, or agin electrons
2. Interaction depends on number of electrons and how they are arranged

21

Like charges repel each other

Unlike charges are attracted to each other

22

Electrons move about the nucleus in shells 3

1. An electron shell is the energy level of the electron, may be thought of as an orbit
2. Electrons travel in orbitals
3. Each orbital cab hold no more than two electrons

23

Orbitals are

Wave like mathematical function describing where an electron is

24

Hydrogen 2

1. Simplest atom
2. Consist of a single electron in one shell

25

Shells around a nucleus equivalent to energy levels 2

1. Shell closest to nucleus at lowest energy level
2. Each shell further out at progressively higher energy levels

26

A shell can have up to eight electrons

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27

Inert atoms are

Atoms with no vacancies in outer shell

28

Atoms with no vacancies in outer shell 2

1. Said to be inert
2. Usually do not take part in chemical reactions

29

Chemicals bonds 3

1. Links between atoms that form when their electrons interact
2. Chemical bonding joins atoms to form molecules
3. An atom is most stable when it's outer shell is filled

30

Chemical bonding with other atoms can provide

Stability

31

Electron vacancy

Indicates atom will bond with others

32

Compounds 4

1. Combination of two or more elements
2. Element proportions never vary
3. Example: water

33

Water chemical compound

Always consist of one oxygen atom bonded to two hydrogen atoms

34

Mixture 3

1. Two or more kinds of molecules mingle
2. Proportions may be different
3. Example: sucrose and water

35

Atom carries no charge 3

1. Number of protons and electrons are equal
2. Balance can change if atom has a vacancy in outer shell
3. Gain or loss of an electron creates a charged particle called an ion

36

Ionic bond joins atoms with opposite electrical charges

Example: sodium chloride

37

Covalent bond

•occurs when atoms share two electrons
•two atoms each have one electron in outer shell
-needs one more to be complete
•covalent bonds are strong and stable
•notation: single line between two atoms
- double covalent bond indicated by double line
- triple bond had three lines

38

Non polar covalent bond

1. Two atoms pull equally on electrons
2. No charge difference at the two ends( poles)
3. Example: molecular hydrogen

39

Two atoms pull equally on electrons

Share them equally

40

Polar covalent bond 2

1. Two atoms do not pull equally on electrons
2. The one with the most protons pulls more

41

The one with the most protons pulls more

It's end of the bond has a slightly more negative charge

42

Hydrogen bond

Weak link formed between a covalently bonded hydrogen atom and another atom taking part in a separate covalent bond