Structure et modèles de l’atome Flashcards (43 cards)

How did Aristotle and Democritus differ on matter’s structure?

Aristotle proposed continuous matter without free space; Democritus proposed indivisible particles separated by void.

Which year did Dalton propose that matter consists of atoms combining in chemical reactions?

1803.

Which model did Thomson propose in 1904?

The Thomson pudding, or raisin-bread, model.

Which year did Rutherford propose the planetary model of the atom?

1911.

Which year did Niels Bohr propose his model of fixed electron orbits?

1913.

Which year did Erwin Schrödinger propose an electron-cloud model?

1927.

What happened to most alpha particles in Rutherford’s gold-foil experiment?

They passed through the foil.

Which observation led Rutherford to conclude that atoms are mostly empty space?

Most alpha particles passed through the gold foil.

What did Rutherford infer about the nucleus from alpha particles being deflected back?

The nucleus is very small, much heavier than the electron space, and positively charged.

Who discovered the neutron, and in which year?

James Chadwick discovered it in 1932.

What charge does a neutron have?

It has no charge.

What role does the course attribute to the neutron in the nucleus?

It contributes to the cohesion of protons in the nucleus.

What is an atom, and what two parts does it contain?

It is the smallest entity constituting matter, with a nucleus and an electron cloud.

What is the overall electrical charge of an atom?

It is electrically neutral.

How do proton and electron counts compare in a neutral atom?

They are equal.

Which particles make up an atomic nucleus?

Protons and neutrons.

Which particles are found in an atom’s electron cloud?

Electrons.

In atomic notation $^{A}_{Z}X$, what does $X$ represent?

The element’s symbol.

In atomic notation $^{A}_{Z}X$, what does $A$ represent?

The number of nucleons.

In atomic notation $^{A}_{Z}X$, what does $Z$ represent?

The number of protons.

For a neutral atom, what does the atomic number $Z$ equal?

The number of electrons.

What formula gives an atom’s neutron number $N$?

$N=A-Z$

What accounts for nearly all of an atom’s mass?

Its nucleus.

What are the electron-shell names from nearest to farthest from the nucleus?

K, L, and M.

How many electrons saturate the K shell in the presented Bohr model?

2 electrons.

How many electrons saturate each of the L and M shells?

8 electrons.

Which filling rule applies to the first two electrons?

The duet rule.

What forms when an atom gains or loses electrons?

An electrically charged entity called an ion.

What charge does a cation carry after losing electrons?

A positive charge.

What charge does an anion carry after gaining electrons?

A negative charge.

How do atoms tend to satisfy the octet rule?

By gaining or giving up electrons to fill their outer shell.

Which four elements did Aristotle associate with bodily humors?

Water with phlegm, fire with yellow bile, earth with black bile, and air with blood.

How did Dalton represent each chemical element in his atomic model?

As a simple sphere without internal structure.

How are known atoms classified in the periodic table?

By their number of electrons and their electron shells.

What is the approximate radius of an atomic nucleus?

$10^{-15}\,\mathrm{m}$

What is the approximate radius of an entire atom?

$10^{-10}\,\mathrm{m}$

What proton and neutron masses does the course give?

Each is $1.7\times10^{-27}\,\mathrm{kg}$.

How does the course estimate an atom’s mass?

$A\times m_p$.

What is the outermost electron shell, farthest from the nucleus, called?

The valence shell.

How many electrons does neutral sulfur have before forming $\mathrm{S}^{2-}$?

16 electrons.

How many electrons does sulfur gain to form $\mathrm{S}^{2-}$?

2 electrons.

How many electrons does neutral sodium have before forming $\mathrm{Na}^{+}$?

11 electrons.

How many electrons does sodium have after forming $\mathrm{Na}^{+}$?

10 electrons.