25 Sem 1.1

Question 1

What is an element?

Answer 1

A pure substance made of one type of atom (e.g. O₂, Fe).

Question 2

What is a compound?

Answer 2

A substance made from two or more elements chemically bonded (e.g. H₂O).

Question 3

What is a mixture?

Answer 3

A combination of substances not chemically bonded (e.g. air, saltwater).

Question 4

What are protons?

Answer 4

Positive charge (+), in nucleus.

Question 5

What are neutrons?

Answer 5

No charge (0), in nucleus.

Question 6

What are electrons?

Answer 6

Negative charge (–), orbit around nucleus in shells.

Question 7

What is the atomic number?

Answer 7

Number of protons (also equals electrons in neutral atoms).

Question 8

What is the mass number?

Answer 8

Protons + Neutrons.

Question 9

How do you calculate neutrons?

Answer 9

Neutrons = Mass number – Atomic number.

Question 10

What is the electron configuration rule?

Answer 10

Fill electrons into shells: 1st shell: max 2, 2nd shell: max 8, 3rd shell: max 8.

Question 11

What are valence electrons?

Answer 11

Electrons in the outer shell.

Question 12

What is a flame test?

Answer 12

Used to identify elements based on flame color.

Question 13

What is an ion?

Answer 13

An atom that has lost or gained electrons.

Question 14

What is a cation?

Answer 14

Positive ion (lost electrons).

Question 15

What is an anion?

Answer 15

Negative ion (gained electrons).

Question 16

What is the ion symbol for sodium?

Answer 16

Na⁺.

Question 17

What is the ion symbol for chlorine?

Answer 17

Cl⁻.

Question 18

What is the ion symbol for magnesium?

Answer 18

Mg²⁺.

Question 19

Why do ions form?

Answer 19

To achieve a full outer shell.

Question 20

What are groups in the periodic table?

Answer 20

Columns with elements that have the same number of valence electrons.

Question 21

What are periods in the periodic table?

Answer 21

Rows with elements that have the same number of electron shells.

Question 22

Where are metals located in the periodic table?

Answer 22

Left/middle.

Question 23

Where are non-metals located in the periodic table?

Answer 23

Right.

Question 24

What are alkali metals?

Answer 24

Group 1 elements, very reactive, soft, with 1 valence electron.

Question 25

What are alkaline earth metals?

Answer 25

Group 2 elements, reactive, with 2 valence electrons.

Question 26

What are halogens?

Answer 26

Group 17 elements, reactive non-metals, with 7 valence electrons.

Question 27

What are noble gases?

Answer 27

Group 18 elements, stable, with a full outer shell.

Question 28

What are transition metals?

Answer 28

Middle section of the periodic table with various charges.

Question 29

How does reactivity trend for metals?

Answer 29

Reactivity increases down a group.

Question 30

How does reactivity trend for non-metals?

Answer 30

Reactivity increases up a group.

Question 31

What is an isotope?

Answer 31

Same number of protons, different number of neutrons (e.g. Carbon-12 vs Carbon-14).

Question 32

What is a radioisotope?

Answer 32

An unstable isotope that undergoes radioactive decay.

Question 33

Why is atomic mass a decimal?

Answer 33

It's an average of all isotopes.

Question 34

What is radioactive decay?

Answer 34

When unstable nuclei lose particles/energy to become stable.

Question 35

What is half-life?

Answer 35

The time it takes for half of a radioactive substance to decay.

Question 36

How can you determine remaining substance after several half-lives?

Answer 36

Use graph to read when half is gone.

Question 37

What is radiometric dating?

Answer 37

Measures remaining isotopes to date fossils/rocks.

Question 38

What are the types of radiation?

Answer 38

Alpha (α, +2, stopped by paper), Beta (β, -1, stopped by thin metal), Gamma (γ, 0, stopped by thick lead/concrete).

Question 39

What are medical uses of radiation?

Answer 39

Cancer treatment (radiotherapy), tracers.

Question 40

What are industrial uses of radiation?

Answer 40

Sterilizing equipment, detecting leaks.

Question 41

How does nuclear power generate electricity?

Answer 41

Splits atoms (fission) to release energy.

Question 42

What are the positives of nuclear power?

Answer 42

No CO₂, lots of energy.

Question 43

What are the negatives of nuclear power?

Answer 43

Radioactive waste, accidents.

Question 44

What is particle theory?

Answer 44

All matter is made of particles.

Question 45

How does temperature affect particle movement?

Answer 45

Particles move more when heated.

Question 46

What is density?

Answer 46

How compact particles are: Density = Mass ÷ Volume.

Question 47

What is conduction?

Answer 47

Heat transfer through solids (particles collide).

Question 48

What is convection?

Answer 48

Heat transfer in liquids/gases (hot rises, cold sinks).

Question 49

What is radiation?

Answer 49

Heat transfer via electromagnetic waves (no medium needed).

Question 50

What are transverse waves?

Answer 50

Vibrate up and down, energy moves sideways.

Question 51

What are the parts of a transverse wave?

Answer 51

Crest (top), Trough (bottom), Wavelength (distance between crests), Amplitude (height of wave).

Question 52

What are longitudinal waves?

Answer 52

Vibrate back and forth.

Question 53

What are the parts of a longitudinal wave?

Answer 53

Compression (particles close), Rarefaction (particles spread out).

Question 54

What is frequency?

Answer 54

Number of waves per second.

Question 55

How do you calculate wave speed?

Answer 55

Wave Speed = Frequency × Wavelength.

Question 56

What does higher frequency indicate?

Answer 56

Higher pitch (sound) or energy (light).

Question 57

What is sound?

Answer 57

Vibration of particles.

Question 58

What does sound need to travel?

Answer 58

A medium (air, water, etc.).

Question 59

How does density affect sound speed?

Answer 59

More dense = faster sound.

Question 60

How does light travel?

Answer 60

In waves, doesn’t need a medium.

Question 61

What happens to light speed in different materials?

Answer 61

Speed changes → refraction.

Question 62

What is the law of reflection?

Answer 62

Angle of incidence = angle of reflection.

Question 63

What is refraction?

Answer 63

Light bends when it changes speed between materials.

Question 64

What are the effects of light interactions with surfaces?

Answer 64

Mirror (reflection), Convex mirror (spreads rays), Concave mirror (focuses rays), Convex lens (focuses light), Concave lens (spreads light), Prism (splits light).

Question 65

What is dispersion?

Answer 65

White light splits into rainbow colors through a prism.

Question 66

What are the parts of the eye?

Answer 66

Cornea (bends light), Iris (controls light), Lens (focuses light), Retina (light sensors), Optic nerve (sends signal to brain).

Question 67

What is short-sightedness?

Answer 67

Can't see far → focus in front of retina.

Question 68

What is long-sightedness?

Answer 68

Can't see near → focus behind retina.

Question 69

What is the electromagnetic spectrum?

Answer 69

Types include Radio (long, broadcasting), Microwave (shorter, cooking), Infrared (shorter, night vision), Visible (light, human vision), Ultraviolet (shorter, tanning), X-ray (shorter, imaging bones), Gamma (shortest, cancer treatment).