Chemical connection to Biology

Question 1

What is an element?

Answer 1

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

Question 2

Naturally occurring elements

Answer 2

92 elements

Question 3

What is a compound?

Answer 3

a substance consisting of two or more elements in fixed proportion

Question 4

A compound has same characteristics as its elements.True or False

Answer 4

False
compound has different characteristics from its elements Eg.NaCl

Question 5

Essential elements for organisms

Answer 5

Oxygen,Nitrogen,Hydrogen and Carbon-make up 96% of living matter

Ca,P,K,S,Na,Cl and Mg-4%

Question 6

What are trace elements?

Answer 6

Iron and Iodine

Question 7

Smallest unit of matter

Answer 7

An atom

Question 8

The subatomic particles and their charge

Answer 8

Proton——>positive charged
Electron——>negative charged
Neutrons——->Neutral

Question 9

Mass of subatomic particles

Answer 9

Proton-1amu or 1 dalton
Neutron-1amu or 1 dalton
Electron-negligible

Total mass of an atom mainly comes from proton and neutron

Question 10

What is atomic number?

Answer 10

Number of protons in the nucleus

Question 11

What is mass number?

Answer 11

Number of protons+number of neutrons

Question 12

What is isotope?

Answer 12

Atom that contains same number of protons but different number of neutrons.

Atomic number same but different mass number

Question 13

Is it correct in a stable isotope their nucleus do not have a tendency to lose subatomic particles?

Answer 13

Yes

Question 14

What is radioactive isotope?

Answer 14

A radioactive isotope ,the nucleus decays spontaneously and giving off particles and energy.

Question 15

What happens a radioactive isotope decays?

Answer 15

It cause changes in the number of protons and it transforms the atom to an atom of different element.

Eg.if Carbon 14 decays,it loses a proton and becoming Nitrogen

Question 16

What is energy?

Answer 16

The capacity to cause change

Question 17

What is potential energy?

Answer 17

The energy possessed by matter because of its location or structure.

Question 18

Potential energy of an electron

Answer 18

The more distant an electron is from the nucleus,the greater its potential energy

Question 19

An electron can exist only at certain energy level.True or false?

Answer 19

True

Question 20

What is energy shell of an electron?

Answer 20

Characteristics average distance from nucleus and certain energy level

Question 21

The energy level of first shell

Answer 21

The first shell is closest to nucleus and electron in this shell have lowest potential energy

Question 22

What happens when an electron absorbs energy?

Answer 22

It moves to shell farther out from the nucleus( move to higher energy level)

Question 23

What happens when an electron lose energy?

Answer 23

It falls back to the shell closer to the nucleus and the lost energy is released as heat

Question 24

What represents Rows of the Periodic Table?

Answer 24

The number of electron shells

Question 25

What represents column of the Periodic Table?

Answer 25

Group of the elements that have the similar properties

Question 26

Chemical behavior of an atom depends on

Answer 26

number of valence electrons in their outermost shell

Question 27

Do proton and neutron take part in chemical reactions?

Answer 27

No,electrons are only responsible for chemical reactions

Question 28

An atom with a completed valence shell is called

Answer 28

unreactive or inert

Question 29

What is orbital?

Answer 29

The 3D space where an electron is found 90% of the time

Question 30

The first shell has ______ orbital

Answer 30

one s orbital (Spherical)

Question 31

The second shell has______ orbitals

Answer 31

One s orbital (spherical) and three p orbital(dumbbell) total four orbitals

Question 32

How many electrons can occupy in single orbital?

Answer 32

2

Question 33

What are strongest kind of chemical bonds?

Answer 33

Covalent bonds Ionic bonds in dry ionic compounds(due to lattice structure) Ionic bonds in aqueous solution are weak interaction

Question 34

How covalent bond can be formed?

Answer 34

By sharing a pair of valence electrons between two atoms

Question 35

What is electronegativity?

Answer 35

The tendency of an atom to attract an shared electron

Question 36

What is octet rule?

Answer 36

The atom need to have 8 electrons in their outermost shell to thermodynamically stable

Question 37

Non polar covalent bond

Answer 37

Electronegativity difference between 2 atoms is 0-0.4 so the electrons are shared equally

Question 38

Polar covalent bond

Answer 38

Electronegativity differences between two atoms is 0.4-1.9 So electrons spend more time near the more electronegative elements forming partial positive charge and partial negative charge

Question 39

Electronegativity differences in Ionic bond

Answer 39

greater than 1.9

Question 40

What happens in ionic bond?

Answer 40

Electrons are given off to more electronegative elements forming ions of opposite charged

Question 41

Types of ions

Answer 41

Positive ions-Cation Negative ions-Anion Cats are Pussytive

Question 42

What is intramolecular force?

Answer 42

Forces between different atoms inside a molecule Responsible for shape,stability and reactivity

Question 43

What is intermolecular force?

Answer 43

Forces that exist between molecules in space

Question 44

What is hydrogen bond?

Answer 44

bond between H and O,N,F

Question 45

What is chemical reaction?

Answer 45

The making and breaking of bonds leading to changes in composition of matter is called chemical reaction

Question 46

All chemical reactions are theoretically reversible,True or False?

Answer 46

True

Question 47

What is chemical equilibrium?

Answer 47

The chemical equilibrium is reached when the forward and reverse reaction rates are equal