Atomic Structure and Periodicity

Flashcards covering the key concepts from the lecture notes on atomic structure and periodicity.

What is the central part of an atom that contains protons and neutrons called?

Nucleus

According to Democritus, matter consists of small indivisible particles called __.

Atoms

Who developed the first useful atomic theory around 1808?

John Dalton

What is Dalton's Atomic Theory assumption about compounds?

Compounds are formed by the union of two or more different elements.

What is the average atomic mass of an element influenced by?

The isotopes and their fractional abundance.

What did the Law of Conservation of Mass state?

Matter is neither created nor destroyed in a chemical reaction.

What are isotopes that emit radiation called?

Radioactive isotopes.

What type of particles do cathode rays consist of?

Electrons.

What is the charge of an electron?

Negative.

Which principle states that it is impossible to know both position and momentum of a particle with certainty?

Heisenberg's Uncertainty Principle.

What is the fundamental unit of electric charge called?

Electron.

What explains the emission of light when electrons transition between energy levels?

Photon emission.

What did Bohr’s model of the hydrogen atom introduce?

Quantized energy levels for electrons.

According to Dalton, what are all substances composed of?

Indivisible particles called atoms.

What type of reaction involves the breakdown of a nucleus and emits radiation?

Radioactivity.

What term describes the average mass of an element based on its isotopes?

Average atomic mass.

What is responsible for the theory that certain properties of an atom can only have specific values?

Quantum theory.

Define the atomic number of an atom.

The number of protons present in the nucleus.

What is the model of the atom proposed by Ernest Rutherford?

A small positively charged nucleus with electrons surrounding it.

What type of energy is released when an electron transitions to a lower energy level?

Photon energy.

How does ionization energy change across a period in the periodic table?

It generally increases from left to right.

What is an atom that gains electrons called?

Anion.

Which scientist is known for discovering the neutron?

James Chadwick.

What is the mass number of an atom defined as?

The total number of protons and neutrons in the nucleus.

What are the three laws of chemical combination?

Conservation of mass, definite composition, and multiple proportions.

What is the relationship between energy and frequency of electromagnetic radiation?

E = hν.

What is the relationship between energy and wavelength of electromagnetic radiation?

E = hc/λ.

Define the term 'electron affinity.'

The energy change when an electron is added to an isolated gaseous atom.

What quantum number designates the principal energy level?

Principal quantum number (n).

What is the maximum number of electrons in a shell given by?

2n^2.

Is the atomic mass shown in the periodic table a whole number? Why or why not?

No, it’s a weighted average of all isotopes of an element.

What does the Pauli Exclusion Principle state?

No two electrons can have the same set of four quantum numbers.

What are the two main types of particles in a nucleus?

Protons and neutrons.

Define 'cations.'

Positively charged ions formed by losing electrons.

What phenomenon occurs when an electron absorbs energy and moves to a higher orbit?

Excitation.

What are the two subatomic particles that contribute almost all of an atom's mass?

Protons and neutrons.

What results from the emission of photons when electrons fall from high energy levels?

Spectral lines.

What does the azimuthal quantum number (l) indicate?

The shape of the orbital.

Which group of the periodic table consists of highly electronegative elements?

Halogens.

What is the general trend of atomic radii across a period?

Atomic radii decrease from left to right.

What is the term for elements that have similar chemical properties and are found in the same column of the periodic table?

Groups or families.

When elements react, in what proportions do they combine according to the Law of Definite Composition?

In specific mass proportions.

Which principle explains that electrons occupy the lowest energy orbitals first?

Aufbau’s Principle.

What atomic theory states that atoms are indivisible particles?

Dalton’s Atomic Theory.

What isotopes are produced through radioactive decay?

Radioactive isotopes.

Over what range of energy does the electromagnetic spectrum extend?

From very low (radio waves) to very high (gamma rays) frequencies.

What does the magnetic quantum number (ml) describe?

The orientation of an orbital in space.

Which subatomic particle has a mass approximately 1/2000 that of a proton?

Electron.

What does the term 'isoelectronic' mean?

Ions with the same electron configuration.

What is the shape of the s orbital?

Spherical.

What is another term for the atomic mass unit (amu)?

Dalton.

What is produced in the decay of alpha particles?

Helium nuclei.

What is the definition of the term 'metallic character'?

The tendency of an element to lose electrons and form cations.

Which group of elements is characterized as the alkaline earth metals?

Group IIA.

Define the term 'effective nuclear charge.'

The net positive charge experienced by an electron in a multi-electron atom.

What type of ionization energy is the energy required to remove an electron from a neutral atom?

First ionization energy.

What is described by the term 'electron cloud model'?

The modern view of the atom where electrons move in probabilities around the nucleus.

What leads to the emission spectrum of an atom?

The transition of electrons between energy levels.

Which rule states that every orbital in a subshell is singly occupied before any orbital is doubly occupied?

Hund's Rule.

What happens to elements’ ionization energies when moving down a group?

They generally decrease.

What does the quantum number 's' indicate?

The shape of the s orbital (spherical).

What is the fundamental aspect of light as proposed by Max Planck?

Light has both wave and particle properties.

Which atomic model introduced the concept of quantized energy levels?

Bohr's atomic model.

What does a high-frequency emission correspond to in terms of wavelength?

A shorter wavelength.

What distinguishes alkali metals from alkaline earth metals?

Alkali metals are in Group IA while alkaline earth metals are in Group IIA.

What is the significance of the number of valence electrons in determining chemical properties?

They dictate how an element reacts chemically.

In terms of stability, why are filled or half-filled d subshells significant?

They confer extra stability to the atom's electronic configuration.

What is the process called when a neutral atom gains energy and loses an electron?

Ionization.

Define the term 'quantum mechanical model.'

A modern description of the atom that incorporates wave behavior.

What changes occur in an atom when it transitions from a higher to a lower energy level?

Energy is released as a photon.

What is the relative size of cations compared to their neutral atoms?

Cations are smaller than their neutral atoms.

What experimental evidence supported the idea of subatomic particles?

Cathode ray experiments.

Which quantum number indicates electron spin?

Spin quantum number (ms).

Who proposed the theory of matter-wave duality?

Louis de Broglie.

What determines the energy of a photon emitted from an atom?

The difference in energy between two electron energy levels.

What is the central concept of modern atomic theory?

Atoms consist of electrons in a probabilistic cloud around a nucleus.