Chapter 2: The Chemical Context of Life Flashcards Preview

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Flashcards in Chapter 2: The Chemical Context of Life Deck (31):
1

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

compound

2

those required by an organism in only minute quantities

Trace elements

3

dense core

atomic nucleus

4

-written as a subscript to the left of the symbol for the element
-tells us the number of protons and also the number of electrons in an electrically neutral atom

atomic number

5

sum of protons plus neutrons in the nucleus of an atom

mass number

6

we can determine the number of neutrons by subtracting the _______ from the _______

atomic number ;mass number

7

different atomic forms

isotopes

8

the nucleus decays spontaneously, giving off particles and energy

radioactive isotope

9

capacity to cause change

Energy

10

energy that matter possesses because of its location or structure

potential energy

11

different states of potential energy that electrons have in an atom

energy levels

12

An electrons energy level is correlated with its average distance from the nucleus; these average distances are represented symbolically by ___________

electron shells

13

outer electrons

valence electrons

14

outermost electron shell

valence shell

15

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

orbital

16

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

element

17

sharing of a pair of valence electrons by two atoms

covalent bond

18

two or more atoms held together by covalent bonds

molecule

19

a pair of shared electrons

single bond

20

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

electronegativity

21

a charged atom (or molecule) is called an

ion

22

negatively charged ion

anion

23

compounds formed by ionic bonds are called

ionic compounds or salts

24

when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom

hydrogen bond

25

the point at which the reactions offset one another exactly

chemical equilibrium

26

the process that produces sugar (glucose) and oxygen from carbon dioxide and water

photosynthesis

27

weak and occur only when atoms and molecules are very close together

van der Waals interactions

28

because of their opposite charges, cations and anions attract each other; this attraction is called an _____

ionic bond

29

isotopes of an element will always differ in ______

atomic mass

30

a hydrogen bond is _____

a weak chemical bond

31

hydrogen bonds occur when ____

partial opposite charges on molecules come close enough to attract eachother