NMAT

Question 1

Matter

Answer 1

anything that has mass and occupies space

Question 2

Mixtures

Answer 2

combinations of 2 or more substances in which each substance retains its own chemical identity and properties

Question 3

Compound

Answer 3

substance composed of 2 or more elements chemically combined in fixed proportions

Question 4

Element

Answer 4

substance that cannot be decomposed by any chemical reaction into simpler substances

Question 5

Law of Conservation of Mass

Answer 5

total mass of the products of a chemical reaction is the same as the total mass of the reactants (mass remains constant during chemical reaction)

Question 6

Law of Conservation of Mass

Answer 6

total mass of the products of a chemical reaction is the same as the total mass of the reactants (mass remains constant during chemical reaction)

Question 7

Law of Definite Composition

Answer 7

the elemental composition of a pure compound is always the same, regardless of its source

Question 8

Law of Multiple Proportions

Answer 8

2 elements form more than one compound, the masses of one element in these compounds for a fixed mass of the other element are in ratios of small whole numbers

Question 9

Atomic Number

Answer 9

no. of protons in nucleus

Question 10

Mass number

Answer 10

protons + neutrons

Question 11

Isotopes

Answer 11

atoms of the same element with different mass numbers

Question 12

Atomic Mass Unit

Answer 12

exactly 1/12th the mass of a carbon-12 atom

Question 13

Atomic Mass

Answer 13

average mass of the atoms of an element in amu; mass in g of one mol of the element

Question 14

Mole

Answer 14

quantity of a given substance that contains as many molecules or formula units as the no. of atoms in exactly 12 g of carbon-12; consists of 6.02 x 10^23 particles

Question 15

Molar Mass

Answer 15

mass of one mol of substance; in g it is numerically equal to the formula mass (weight) in atomic mass units

Question 16

Mass % of A

Answer 16

(mass of A in whole/mass of the whole) x 100%

Question 17

Molecule

Answer 17

definite group of atoms chemically bonded together

Question 18

Ion

Answer 18

electrically charged particle obtained from an atom or chemically bonded group of atoms by adding or removing electrons

Question 19

Chemical formula

Answer 19

notation that uses atomic symbols with numerical subscripts to convey the relative proportions of atoms of the different elements in the substance

Question 20

Empirical Formula

Answer 20

formula with the smallest integer subscripts

Question 21

Molecular Formula

Answer 21

chemical formula that gives the exact number of different atoms of an element in a molecule

Question 22

Molecular Mass/Weight

Answer 22

the sum of the atomic masses/weights of all the atoms in a molecule

Question 23

Formula Mass/Weight

Answer 23

the sum of the atomic masses/weights of all atoms in a formula unit of the compound, molecular or not

Question 24

Empirical Formula Mass/Weight

Answer 24

the sum of the atomic masses divided by the weights of all the atoms in an empirical formula

Question 25

Molecular Formula

Answer 25

n x Empirical Formula where n = molecular or formula weight / empirical formula weight

Question 26

Stoichiometry

Answer 26

calculation of the quantities of reactants and products involved in a chemical reaction

Question 27

Limiting Reactant or Reagent

Answer 27

reactant that is entirely consumed when a reaction is completed

Question 28

Theoretical Yield

Answer 28

quantity of product that is calculated to form when all of the LR reacts

Question 29

Actual Yield

Answer 29

amount of product actually obtained in a reaction

Question 30

Percentage Yield

Answer 30

(actual yield / theoretical yield) x 100%

Question 31

________ Atomic Theory

Answer 31

Dalton’s

Question 32

Main postulates of the atomic theory

Answer 32

Matter is composed of very tiny or microscopic particles called atom 1. Atom is an indivisible particle 2. Atom can neither be created nor destroyed 3. Atoms of an element are identical in size, shape, mass, and in other properties 4. Atoms of different elements are different in their properties 5. Atoms combine with each other in small whole numbers 6. All chemical reactions are due to the combination or separation of atoms

Question 33

Defects in Dalton’s Theory

Answer 33

- Atoms can be divided into a number of sub-atomic particles (electrons, protons and neutrons) - Atoms of an element may be different in their masses - Not all compounds have small number of atoms - Atoms can be destroyed by fission process (atom bomb, nuclear reactor)

Question 34

Nuclear Atomic Model

Answer 34

Protons and Neutrons in the nucleus; electrons outside the nucleus

Question 35

Heisenberg’s Uncertainty Principle

Answer 35

it is impossible to determine simultaneously the exact position and the exact momentum of a fast moving body like an electron

Question 36

Pauli’s Exclusion Principle

Answer 36

no 2 electrons in the same atom may have the same set of all 4 quantum numbers

Question 37

Hund’s Rule of Multiplicity

Answer 37

in the ground state of an atom, electrons are distributed among the orbitals of a sub-shell in a way that gives the maximum number of unpaired electrons with parallel spins

Question 38

Aufbau Principle (Building up Principle)

Answer 38

a scheme used to reproduce the electronic configurations of atoms by successively filling sub-shells with electrons in a specific order (orbitals with lower energy first)

Question 39

Atomic Size

Answer 39

within a period - decreases from left to right within a group - increases from top to bottom

Question 40

Size of Cation

Answer 40

within a period - decreases from left to right within a group - increases from top to bottom

Question 41

Size of Anion

Answer 41

within a period - decreases from left to right within a group - increases from top to bottom

Question 42

Ionization Energy

Answer 42

energy needed to remove an electron from a gaseous atom in the ground state within a period - increases from left to right within a group - decreases from top to bottom

Question 43

Electron Affinity

Answer 43

energy change when an electron is added to a gaseous atom in the ground state within a period - increases negative value from left to right within a group no clear trend

Question 44

Basicity of Metal Oxides

Answer 44

within a period - decreases from left to right within a group - increases from top to bottom

Question 45

Acidity of Non-metal Oxides

Answer 45

within a period - increases from left to right within a group - decreases from top to bottom

Question 46

Metallic (Reducing) Property

Answer 46

within a period - decreases from left to right within a group - increases from top to bottom

Question 47

Non-Metallic (Oxidizing) Property

Answer 47

within a period - increases from left to right within a group - decreases from top to bottom

Question 48

Electronegativity

Answer 48

measure of the ability of an atom in a molecule to draw bonding electrons to itself within a period - increases from left to right within a group - decreases from top to bottom

Question 49

Electrovalent Bond (Ionic)

Answer 49

formed by transfer of electrons to form ions

Question 50

Covalent Bond

Answer 50

formed by sharing of electrons between atoms

Question 51

Formal Charge and what does it mean?

Answer 51

Group number - number of unshared electrons - number of covalent bonds the higher the bond order, the shorter the bond length and the greater the bond strength

Question 52

Metallic Bond

Answer 52

a crystal of the metal consists of a regular arrangement of the positive ions, and the valence electrons move throughout the crystal attracted to the positive cores of all the positive ions

Question 53

Non-polar Covalent Bond

Answer 53

equal sharing of a pair of electrons in diatomic molecules consisting of identical atoms in identical atoms with identical neighbors

Question 54

Polar Covalent Bond

Answer 54

unequal sharing of a pair of electrons in identical atoms with different neighbors when two bonded atoms are dissimilar

Question 55

What kind of molecule has symmetrical polar bonds?

Answer 55

non-polar molecules

Question 56

What kind of molecule has asymmetrical polar bonds?

Answer 56

Polar molecules

Question 57

Shape of molecule with 6-2 Bonding e-pairs

Answer 57

6: octahedral 5: square pyramidal 4: square planar 3: T-shaped 2: linear

Question 58

Hybrid Orbitals

Answer 58

mixing of atomic orbitals to form a hybrid; the number of hybrid orbitals is equal to the number of pure atomic orbitals that mixed

Question 59

Phases of Matter

Answer 59

1. Ion-dipole 2. Dipole-dipole 3. London forces / Van der Waals forces 4. H-bonding