Sci 9

What is the significance of elements in the same group on the periodic table?

They have similar chemical properties.

What are metals known for in terms of conductivity?

They are good conductors of heat and electricity.

What is the valence shell?

The outermost shell of an atom.

How is the atomic number defined?

It is equal to the number of protons in an element's nucleus.

What correlates loosely with increasing atomic number on the periodic table?

Increasing atomic mass for most elements.

What characterizes alkali metals?

They are highly reactive metals.

What are halogens?

They are highly reactive non-metals.

Why are noble gases unreactive?

They have complete valence shells, making them stable.

What determines the chemical behavior of an atom?

The electron configuration and arrangement of electrons in orbitals.

What is the maximum number of electrons the s orbital can hold?

2 electrons.

How many electrons can the p orbital hold?

6 electrons (3 suborbitals with 2 electrons each).

What is the maximum number of electrons that the d orbital can hold?

10 electrons (5 suborbitals with 2 electrons each).

How many electrons can the f orbital contain?

14 electrons (7 suborbitals with 2 electrons each).

What shape is the s orbital?

Spherical in shape.

What shapes represent the p orbital?

Three mutually perpendicular dumbbell shapes (px, py, pz).

What does the principal quantum number (n) indicate?

The energy level or shell of an orbital.

What is the function of the angular momentum quantum number (l)?

It determines the shape (s, p, d, f) of the orbital.

What does the magnetic quantum number (ml) specify?

The orientation of an orbital within its sublevel.

What do the possible values of the spin quantum number (ms) indicate?

The two possible spin states (+1/2 or -1/2) of an electron.

What is the Pauli Exclusion Principle?

It prevents two electrons in an atom from occupying the same exact quantum state.

What did John Dalton’s atomic theory propose?

Atoms are indivisible and indestructible units.

What did J.J. Thomson discover through his cathode ray experiments?

The electron, a negatively charged subatomic particle.

What was the key feature of Thomson's atomic model?

Positively charged particles scattered throughout a sphere of negative charge.

What did Rutherford's gold foil experiment reveal?

The existence of a small, dense nucleus that deflects most particles.

What concept did Bohr's model introduce?

Quantized energy levels where electrons exist in specific energy states.

Why was Bohr's model primarily successful?

It successfully explained the spectrum of hydrogen atoms due to its simplicity.

What limitation did Bohr's model have?

It struggled to explain spectra of atoms with multiple electrons.

What does the quantum mechanical model define?

Orbitals, regions of space where electrons are most likely to be found.

What does the Heisenberg Uncertainty Principle state?

It is impossible to know both the exact position and momentum of a particle simultaneously.

What are electrons?

Negatively charged subatomic particles that orbit the nucleus.

What does electron configuration describe?

The distribution of electrons in an atom's orbitals.

What does the Aufbau Principle state?

Electrons fill orbitals in order of increasing energy.

How does electron configuration help in chemistry?

It helps understand physical and chemical properties, predict reactivity, and explain bond formation.

What is the nature of ionic bonds?

They form when one atom transfers electrons to another, creating oppositely charged ions.

What happens to ionic compounds when dissolved in water?

They dissociate into their constituent ions, which can conduct electricity.

What is a cation?

A positively charged ion formed by the loss of one or more electrons.

What is an anion?

A negatively charged ion formed by the gain of one or more electrons.

What is sodium chloride made of?

Sodium cations (Na+) and chloride anions (Cl-).

What do ionic compounds form to maximize attraction?

Crystal lattices.

What is the formula for the compound formed by calcium and chlorine?

CaCl₂.

What is a polar covalent bond?

It involves unequal sharing of electrons, leading to partial positive and negative charges.

What does the oxygen atom in water have?

A partial negative charge.

What is a characteristic of covalent compounds?

They typically have low melting and boiling points and are poor conductors of electricity.

What are London dispersion forces?

Weak intermolecular forces that occur between nonpolar molecules.

What do dipole-dipole forces occur between?

Polar molecules due to attraction between partial positive and partial negative charges.

What is diamond classified as?

A covalent network solid.

What does hydrochloric acid ionize to form in water?

H+ and Cl- ions.

What is ethylene glycol commonly used for?

As a coolant in car engines due to its high heat capacity.