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#atoms&molecules Flashcards

1
Q

Compound

A

is made of atoms joined by bonds

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2
Q

What determines the property of a compound ??

A

The number of protons determines atoms identity
An atom’s electron distribution determines its ability to form bonds.
A compound’s properties depend on its atoms and how they are bonded together.

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3
Q

Formic Acid

A

HCOOH

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4
Q

Define Compounds

A

Matter consists of chemical elements in pure form and in combinations called Compounds.

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5
Q

Define Matter

A

(Organisms are composed of matter)anything that takes up space and has mass.

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6
Q

Matter is made up of

A

Elements

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7
Q

An element

A

is a substance cannot be broken down to other substance by chemical reactions

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8
Q

How many elements they have identified?

A

92
(Eg.Gold,Copper,Carbon,and oxygen)

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9
Q

Sodium In Latin Name

A

Natrium

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10
Q

Compound Definition

A

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

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11
Q

A compound has a characteristics different from those of its elements

A

eg Nacl(emergent properties)

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12
Q

20-25% essential elements

A

for a healthy life

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13
Q

The essential elements are similar among organisms but there is some variations.

A

Humans need 25 elements but plants need only 17.

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14
Q

C O H N —96%of living matter

A

Remaining 4% Ca, P, K ,S of organisms mass

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15
Q

Trace elements are required in minute qualities

A

Iron is one such example of trace element that is by all forms of life

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16
Q

Property of an element depends upon ??

A

STRUCTURE OF AN ATOM

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17
Q

Define ATOM

A

An atom is the smallest unit of matter that still retains the properties of an element.

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18
Q

Each neutron and proton are almost identical in MASS

A

1.7 X 10^-24 g

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19
Q

Why can we ignore electron when computing total mass of an atom.

A

Neutrons and Protons have masses close to 1 Dalton,because mass of an electron is only about 1/2000 that of neutron or proton.

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20
Q

All atoms of a PARTICULAR ELEMENT have the same number of protons in their nuclei .

A

ATOMIC NUMBER
(unique to an element)

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21
Q

UP mass n0
DOWN atomic no

A

True

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22
Q

Number of Neutrons

A

Mass number -Atomic number

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23
Q

Neutrons and protons each have mass very close to ______

A

1 DALTON

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24
Q

All atoms of a given element have the same number of protons but some atoms have more neutrons than other atoms of the same element

A

Hence greater mass .

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25
Define ISOTOPES
These different atomic forms of the same element
26
Isotopes of carbon
C has the atomic no of 6 Its mass no varies C-12 most common =6 neutrons C-13 1%=7 neutrons C-14 very rare=8 neutrons
27
Although the isotopes of an element have slightly different masses do they have same chemical reactions.
Yes, they behave identically in chemical reactions .
28
For an element with more than one naturally occurring isotope _________
The atomic mass is an average of those isotopes weighted by their abundance.(thus carbon has the atomic mass of 12.01 Dalton)
29
12 carbon 13 carbon are stable isotopes because they do not decay
Their nuclei do not have tendency to lose subatomic particles called DECAY.
30
C 14 is unstable or radioactive
Radioisotope spontaneously gives particles and energy.
31
when a radioactive decays -leads to change in the number of protons it transforms atom to atom of a different element.
Ex:C-14 atom decays,a neutron decays into protons ,transforming the atom into Nitrogen atom.
32
Atoms are mostly empty space
TRUE
33
Only electrons are involved in chemical reactions
TRUE
34
An atom's electron vary in the amount of energy they posses.
TRUE
35
Define ENERGY
The capacity to cause change by doing work .
36
Define POTENTIAL ENERGY
Energy that matter posses because of its location or structure
37
Matter has natural tendency to move toward the lowest possible state of potential energy.
TRUE
38
The electrons has the potential energy due to _____
their distance from the nucleus .(the negatively charged electrons are attracted to positively charged nucleus)
39
Electrons exist only at fixed fixed levels of potential energy
Electron shells
40
When can an electron move ??
can move from one shell to other shell only if the energy it gains or loses is exactly equal to the difference in energy between the energy levels of the two shell.
41
Energy absorbed
away from the nucleus
42
Energy lost
Toward the nucleus
43
It takes work to move a given electron farther away from the nucleus __ ____
so the more distant an electron is from the nucleus ,the greater its potential energy .
44
An electron's potential energy is determined by its energy level
An electron can exist only at a certain energy levels,not between them.
45
An electron's energy level is correlated with its average distance from the nucleus.
TRUE
46
Chemical behavior of an atom depends mostly on the number of electrons in the outermost shell.
Called valence shell electrons
47
In reality,we can never know the exact location of the electron
Instead we know the space in which an electron spend most of its time .
48
Define orbital
The three dimensional space where an electron is found 90%of the time.
49
2n^2
Max no of electrons where n = shell or energy level no
50
Subshells
S P D F
51
SUB SHELLS NO OF ORBITALS S 1 P 3 D 5 F 7
no of electrons 1 X 2 = 2 3 X 2=6 5 X 2=10 7 X 2 =14
52
Orbitals is where you precisely find electrons
Each orbitals can hold up to 2 electrons [refer 01&02]
53
Orbital is component of an electron shell
TRUE
54
no of pr=no of el??
Yes only when uncharged
55
Explain electron shells
The first electron shell has only one spherical S orbital called 1s. The second shell has four orbitals: one large spherical s orbital called 2s.&three dumbbell shaped p orbitals called 2p orbitals.....
56
No more than 2 e can occupy single orbital.True or false?
TRUE
57
There are four orbitals in second shell will it have same energy ?
YES, nearly same energy,but they move in different volumes of space.
58
Reactivity depends on________
Presence of unpaired electrons .
59
The formation and function of molecules and ionic compounds depends on ____
CHEMICAL BONDING
60
The strongest kind of chemical bonds are ________ in molecules and __________ in dry ionic compound
Covalent bond,Ionic bond [Ionic bonds in aq.solutions or water based solutions are weak ]
61
The bonding capacity is called the atom's ____
VALENCE [usually equals to no of electrons required to complete the atom's outermost(valence) shell]
62
H2 & O2 is it elements or compound??
It is pure elements because a compound is combination of two or more different elements .
63
Define Electronegativity
The attraction of particular atom for the electrons of a covalent bond .
64
Non-polar covalent
Electrons are shared equally due to same EN.
65
Polar covalent bond
Electrons of the bond aren't shared equally.
66
is CH 4 IS POLAR ??
Yes,much less polar because EN of C&H is almost similar.
67
Positively charged ion called as Negatively charged ion is called as
Cation Anion
68
Define IONIC BOND
Because of their opp charges [cation and anion ] attract each other ..this attraction is called as ionic bond .
69
How does transfer of electron happens ? Explain in detail...
The transfer of electrons is not by itself or by the formation of bonds ..first it allows to form the bond because it results in two ions of opposite charge can form an ionic bond.
70
The ions do not need to have acquired their charge by an electron transfer with each other.True/False?
TRUE
71
Electron transfer &Ionic bonding
Ionic bond is the attraction btw tow opp charged atoms or ions.An ionic bonding can happen even when there is no transfer of electrons
72
IONIC COMPOUND [Salt Crystal]
aggregate of vast no of cations and anions bonded by their electrical attraction and arranged in 3D lattice .
73
COVALENT COMPOUND
which consist of molecules having a definite size&no of atoms .
74
Ionic bond does not consists of molecules . Not all salts have equal amt of anion and cation .TRUE/FALSE.
TRUE
75
The ionic bond are much weaker in aq because -________
each ion is partially shielded by its interactions with water molecules.
76
Weak chemical interactions
Ionic Hydrogen Van der Waals
77
Define Hydrogen bonds
The non covalent attraction btw a hydrogen and an EN atom is H-bond. [Weak temporary attraction is called H-bond.]
78
How to consider whether the compound is considered covalent or not?
When we have a non-metal and a non-metal the compound is usually considered covalent.
79
Non polar covalent compound can have +ve and -ve charged regions. TRUE/FALSE
TRUE because electrons are not always distributed evenly.The results are ever-changing regions of +ve and -ve charge enable all atoms and molecules to stick to one another
80
When does formation of van der waals interaction takes place ??
Occurs only when atoms and molecules are very close together.
81
When many such interaction occurs simultaneously they can be powerful. Give one such eg for above mentioned statement.
Gecko Lizard
82
Can weak interaction form btw large molecules??
Yes,Van der Waals interaction,hydrogen bonds,ionic bonds &other weak interactions may form not only btw molecules but also btw parts of large molecules.[protein or nucleic acids]
83
Importance of weak interaction?
The cumulative effect of weak interactions is to reinforce the three-dimensional shape of the molecule.
84
Shapes are determined by _______
position of the atoms; orbitals.
85
When does atom undergoes rearrangement?
When an atom forms covalent bonds,the orbitals in its valence shell undergo rearrangement .
86
Molecular shape is crucial..explain the statement
It determines how biological molecules recognize and respond to one another with specificity. [Opiates & endorphins]
87
Raw material for photosynthesis are ?
C02 & H2O
88
All chemical reactions are theoretically reversible
One of the factors that affects the rate of rxn is the conc. of reactants .
89
Dynamic Equilibrium
Rxn still going on in both directions ,but with no net effect on the conc. of reactant &products.
90
Equilibrium
Equilibrium does not mean that reactants and products are = in conc.,but their conc. have stabilized at a particular ratio.

ATOMS AND MOLECULES (1 decks)

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