Early Atomic Models and Discoveries

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Questions and Answers

How can the number of neutrons in an atom be calculated?

By adding the number of protons to the atomic number

By subtracting the atomic number from the number of electrons

By multiplying the atomic number by the mass number

By subtracting the number of protons from the mass number (correct)

What is the empirical formula for glucose (C6H12O6)?

CH2O (correct)

C3H6O3

C1H2O1

C2H4O2

Which of the following describes a cation?

An atom that has gained electrons

An ion with a negative charge

An atom that has lost electrons (correct)

An atom that has a balanced charge

Which of the following molecules is considered a diatomic molecule?

Hydrogen (H2) Signup and view all the answers

Which of these substances is correctly identified as a compound?

Water (H2O) Signup and view all the answers

What defines an ion?

An atom or group of atoms with a net positive or negative charge Signup and view all the answers

Which chemical formula represents a molecular compound?

CO Signup and view all the answers

What is the atomic number of an element a measure of?

The number of protons in the nucleus Signup and view all the answers

What is the correct formula for the ionic compound formed between potassium and bromine?

KBr Signup and view all the answers

What is the primary characteristic of the Plum Pudding Model proposed by J.J. Thomson?

The atom is a positively charged jelly-like sphere with negatively charged particles embedded within. Signup and view all the answers

Which systematic name corresponds to the compound Mg(OH)2?

Magnesium hydroxide Signup and view all the answers

What does the Stock System help identify in chemical compounds?

Charge of multivalent metals Signup and view all the answers

Which scientist proposed that electrons occupy discrete orbits and do not radiate energy while in those orbits?

Niels Bohr Signup and view all the answers

What is a key feature of alkali metals in Group 1 of the periodic table?

They react with water to form alkalis, which are strong bases. Signup and view all the answers

What is the defining characteristic of non-metals compared to metals?

They usually exist as gases at room temperature. Signup and view all the answers

What is the name of the binary acid H2S?

Hydrosulfuric acid Signup and view all the answers

Which of the following represents a molecular compound?

SO2 Signup and view all the answers

What is a unique characteristic of noble gases?

They exist naturally as single atoms. Signup and view all the answers

Which of the following statements about metals is correct?

Metals are malleable, ductile, and shine with luster. Signup and view all the answers

How can metalloids be distinguished from both metals and nonmetals?

They possess properties intermediate between metals and nonmetals. Signup and view all the answers

Which term describes elements with similar chemical and physical properties arranged in a systematic way?

Periodic table Signup and view all the answers

What is the correct name for BaCl2?

Barium chloride Signup and view all the answers

What discovery is Ernest Rutherford known for in relation to atomic structure?

Discovering the nucleus as a positively charged center. Signup and view all the answers

What defines the atomic number of an element?

The total number of protons in an atom. Signup and view all the answers

Which prefix is used in the naming of the compound N2O4?

Di- Signup and view all the answers

What is the average atomic mass of an element calculated from?

The isotopic masses weighted by their natural abundances. Signup and view all the answers

What characterizes oxyacids in terms of their composition?

Contain hydrogen, oxygen, and another element Signup and view all the answers

What was a major implication of John Dalton's atomic theory regarding elements and compounds?

The mass ratios of elements in compounds are fixed and integer-based. Signup and view all the answers

If an element has natural abundances of 90.92% with 19.99 amu, 0.26% with 20.99 amu, and 8.82% with 21.99 amu, what is primarily used to determine the average atomic mass of this element?

The isotopes' mass and corresponding abundances. Signup and view all the answers

What are neutrons, as discovered by James Chadwick?

Uncharged particles in the nucleus with a mass approximately equal to that of protons. Signup and view all the answers

Which statement is true about isotopes?

They differ in the mass number due to varying neutrons. Signup and view all the answers

What is true about chlorine and its isotopes?

Chlorine-35 has a greater natural abundance than chlorine-37. Signup and view all the answers

What is the systematic name for HCl?

Hydrochloric acid Signup and view all the answers

What is the systematic name for H2S?

Hydrosulfuric acid Signup and view all the answers

Which naming convention applies if an oxyanion ends in -ate?

Base name of oxyanion–ic + acid Signup and view all the answers

What is the systematic name for HNO2?

Nitrous acid Signup and view all the answers

Which of the following correctly describes a base?

It yields hydroxide ions (OH−) in water. Signup and view all the answers

What is the systematic name for BaCl2 · 2H2O?

Barium chloride dihydrate Signup and view all the answers

What type of hydrocarbon has a benzene ring structure?

Aromatic hydrocarbons Signup and view all the answers

When naming hydrocarbons, what does the suffix -ene indicate?

Presence of a double bond Signup and view all the answers

Study Notes

Early Atomic Models & Discoveries

John Dalton: proposed the atomic theory, which stated that elements are made up of atoms, atoms of the same element are identical, and atoms of different elements have different masses.
J. J. Thomson: discovered electrons and proposed the plum pudding model, which suggested that atoms are positive spheres with negatively charged electrons embedded in them.
Ernest Rutherford: discovered the nucleus of an atom through his gold foil experiment, which showed that positively charged alpha particles were deflected by a concentrated positive charge within the atom.
James Chadwick: discovered neutrons, which are particles with no charge and a mass similar to protons, found in the nucleus of an atom.
Niels Bohr: proposed the Bohr model, which stated that electrons occupy specific energy levels or orbits around the nucleus, and they do not radiate energy while in these orbits.

Periodic Table

The periodic table arranges elements based on their atomic number and recurring chemical properties.
It allows us to predict the properties of elements based on their position on the table.
The periodic table is divided into groups (columns), periods (rows), and blocks.

Metals, Nonmetals, and Metalloids

Metals: good conductors of heat and electricity, malleable (can be hammered into sheets), ductile (can be drawn into wires), and most are solids at room temperature.
Nonmetals: poor conductors of heat and electricity, not malleable or ductile, and vary in state (gas, liquid, or solid) at room temperature.
Metalloids: have properties between metals and nonmetals, often used as semiconductors.

Group Classifications

Group 1 (Alkali Metals): highly reactive metals forming alkalis (strong bases) when reacting with water.
Group 2 (Alkaline Earth Metals): reactive metals forming alkaline earths (oxides that form strong bases).
Group 17 (Halogens): reactive nonmetals producing salts.
Group 18 (Noble Gases): inert gases existing as single atoms.

Atomic Structure Terms

Atomic Number: the number of protons in an atom, defining the element's chemical identity.
Mass Number: the sum of protons and neutrons in the nucleus of an atom.
Isotopes: atoms of the same element with different numbers of neutrons in their nuclei, leading to different mass numbers.
Average Atomic Mass: the weighted average of the masses of all isotopes of an element, accounting for their natural abundance.

Ionic Compounds

Ionic compounds are formed between a metal cation and a nonmetal anion.
The charges of the cation and anion must balance to form an electrically neutral compound.

Nomenclature: Naming Compounds

Ionic Compounds: name the cation followed by the anion, with the anion's name ending in "ide".
Molecular Compounds: use prefixes to indicate the number of atoms of each element, followed by the name of the second element ending in "ide".
Acids: binary acids start with "hydro" followed by the nonmetal's name ending in "ic acid".
Oxyacids: named based on the oxyanion; "-ite" endings for oxyacids mean "-ous acid", while "-ate" endings mean "-ic acid".
Bases: named by adding "hydroxide" to the cation's name.
Hydrates: named with the compound's name followed by a prefix indicating the number of water molecules, ending in "hydrate."

Organic Chemistry

Hydrocarbons: simplest organic compounds containing only carbon and hydrogen atoms.
Aliphatic Hydrocarbons: form straight chains of carbon atoms.
Alicyclic Hydrocarbons: form rings of carbon atoms.
Aromatic Hydrocarbons: contain a benzene ring (C6H6), a special structure.

Naming Hydrocarbons

The name is based on the length of the longest carbon chain (main chain).
The end of the name indicates the type of bond: "-ane" for single bonds, "-ene" for double bonds, and "-yne" for triple bonds.
Branch chains are named with the prefix "-yl" and their position on the main chain is indicated by a number.

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Description

Test your knowledge on the early atomic models and the discoveries of key scientists like Dalton, Thomson, Rutherford, Chadwick, and Bohr. This quiz covers fundamental concepts in atomic theory and the structure of the atom, leading to the arrangement of elements in the periodic table.