Chemistry

Question 1

What are atoms?

Answer 1

Fundamental units of matter, consisting of protons, neutrons, and electrons.

Question 2

How is an element defined?

Answer 2

By its atomic number, which corresponds to the number of protons in its nucleus.

Question 3

What are molecules?

Answer 3

Formed when two or more atoms bond together.

Question 4

What distinguishes pure substances from mixtures?

Answer 4

Pure substances have a uniform and definite composition and cannot be separated by physical means.

Question 5

What are the two categories of pure substances?

Answer 5

Elements and compounds

Question 6

What do molecular compounds consist of?

Answer 6

Two or more nonmetal atoms sharing electrons through covalent bonding.

Question 7

What is a key characteristic of molecular compounds?

Answer 7

Typically have lower melting and boiling points than ionic compounds.

Question 8

What occurs when a liquid’s vapor pressure equals atmospheric pressure?

Answer 8

Boiling.

Question 9

What are the three states of matter?

Answer 9

Solid, Liquid and Gas

Question 10

What is a homogeneous mixture?

Answer 10

A mixture with a uniform composition, like saltwater.

Question 11

What is a heterogeneous mixture?

Answer 11

A mixture containing visibly distinct components, like salad.

Question 12

What is the Rf value in chromatography?

Answer 12

The ratio of the distance traveled by a substance to the distance traveled by the solvent front.

Question 13

Fill in the blank: The first shell of an atom holds up to ______ electrons.

Answer 13

2

Question 14

What determines an atom’s valency?

Answer 14

The number of electrons in its outer shell.

Question 15

What are isotopes?

Answer 15

Variants of the same element that differ in the number of neutrons.

Question 16

What is formula for finding Relative Atomic Mass (RAM)?

Answer 16

(Mass of substance x percent abundance) divided by 100.

Question 17

What are allotropes?

Answer 17

Different forms of the same element that exist in the same physical state.

Question 18

What are cations?

Answer 18

Positively charged ions formed when atoms lose electrons.

Question 19

What is ionic bonding?

Answer 19

Bonding that occurs between a metal and a non-metal through electron transfer.

Question 20

What is covalent bonding?

Answer 20

Bonding that occurs when two non-metal atoms share electrons.

Question 21

What is metallic bonding?

Answer 21

Bonding found in metals where valence electrons are delocalized.

Question 22

What are alkali metals known for?

Answer 22

Being very reactive, especially with water, and forming +1 ions.

Question 23

What is the trend in atomic radius across a period?

Answer 23

It decreases from left to right.

Question 24

What is ionization energy?

Answer 24

The energy required to remove an electron from an atom.

Question 25

What is the trend for electronegativity down a group?

Answer 25

It decreases.

Question 26

What are the key characteristics of ionic compounds?

Answer 26

- High melting and boiling points - Crystalline structures - Conduct electricity when dissolved or melted

Question 27

What happens to melting and boiling points as you move down a group?

Answer 27

They generally increase due to larger atomic sizes.

Question 28

What is the melting point?

Answer 28

The temperature at which a solid becomes a liquid.

Question 29

What is boiling point?

Answer 29

The temperature at which a liquid turns into gas.

Question 30

What trend occurs in melting and boiling points as you move down a group in the periodic table?

Answer 30

Melting and boiling points generally increase due to larger atomic sizes and stronger intermolecular forces.

Question 31

In which groups do melting and boiling points typically decrease down the group?

Answer 31

Groups 1, 2, 13, and 14.

Question 32

What is the exception to metallic elements having high melting points?

Answer 32

Mercury (Hg) has a low melting point of -39°C.

Question 33

What trend is observed in melting and boiling points of Group 1 (Alkali Metals)?

Answer 33

Melting and boiling points decrease down the group.

Question 34

What trend is observed in melting and boiling points of Group 16 (Chalcogens)?

Answer 34

Melting and boiling points increase down the group.

Question 35

What factor influences melting and boiling points due to stronger forces?

Answer 35

Intermolecular Forces.

Question 36

How do larger molecules affect melting and boiling points?

Answer 36

They generally have higher melting and boiling points due to increased van der Waals forces.

Question 37

What is the effect of hydrogen bonding on boiling points?

Answer 37

Molecules capable of hydrogen bonding have significantly elevated boiling points compared to similar-sized molecules without such interactions.

Question 38

Fill in the blank: Ionic compounds exhibit very high melting points due to strong ______ interactions.

Answer 38

ion.