2. Atoms & Elements

The Atom

Atomic Number, Mass Number, and Net Charge

Within the nucleus, the nuclear force keeps it together and the electrostatic force pulls it apart.&nbsp;

Label the following statements about J. J. Thomson’s cathode-ray tube experiments shown in Figure 2.6 as true or false. 
(f) By measuring the deflection of the cathode ray beam caused by electric fields of known strength, the charge-to-mass ratio of the electron was calculated.

Label the following statements about J. J. Thomson’s cathode-ray tube experiments shown in Figure 2.6 as true or false. 
(c) The cathode ray is deflected away from a positively charged plate.

A charged particle moves between two electrically charged
plates, as shown here.
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/17065b87341f11c3-1660580128511.jpg" alt="" />
(a) What is the sign of the electrical charge on the particle?

(a) Thomson’s cathode-ray tube (Figure 2.4) and the mass
spectrometer (Figure 2.11) both involve the use of electric
or magnetic fields to deflect charged particles. What are the
charged particles involved in each of these experiments?

Which experiment and subsequent observation led to the discovery that atoms contain negatively charged particles, now known as electrons? (LO 2.10–2.12)
(a) Oil is sprayed into a chamber and the speed at which the oil droplets fall is measured with and without an applied voltage. X rays in the chamber knock electrons out of air molecules. The electrons stick to the oil pro-ducing an overall negative charge on the drops. Adjusting the voltage changes the speed at which the negatively charged oil droplets fall. 
(b) When a high voltage is applied across metal electrodes at opposite ends of a sealed glass tube, a cathode ray is produced. The cathode ray is repelled by a negatively charged plate. 
(c) A radioactive substance emits alpha particles, which are directed at a thin gold foil. Most of the alpha par-ticles pass through the foil, but a few alpha particles are slightly deflected and some even bounce back toward the radioactive source. 
(d) The mass of different elements in a pure chemical com-pound are measured. Different samples of the compound always contains the same proportion of elements by mass.

An unknown particle is caused to move between two electrically 
charged plates, as illustrated in Figure 2.7. You hypothesize 
that the particle is a proton. (b) Would it be deflected by a 
smaller or larger amount than the b rays?<img src="https://lightcat-files.s3.amazonaws.com/problem_images/af4c471fd97582d7-1664219012312.jpg" alt="" />

The Atom Explained | CHEMISTRY tutorial

An unknown particle is caused to move between two electrically
charged plates, as illustrated in Figure 2.7. You hypothesize
that the particle is a proton. (a) If your hypothesis is
correct, would the particle be deflected in the same or opposite
direction as the b rays?<img src="https://lightcat-files.s3.amazonaws.com/problem_images/0c9cda4348ca5a23-1660560124883.jpg" alt="" />

Atomic Structure And Electrons - Structure Of An Atom - What Are Atoms - Neutrons Protons Electrons

The Atom Example 1

What is an atom | Matter | Physics | FuseSchool

GCSE Chemistry - Atoms & Ions  #1

Find the element in the periodic table with the largest atomic number (Z).

 There is not enough information given to determine the correct answer. 

 The number of protons in an atom is given by the atomic number. 

 Which of the following atoms has the greatest number of protons? 

Determine whether each of the following statements is true
or false. If false, correct the statement to make it true: (d) The
protons in the nucleus of the helium atom are held together
by a force called the strong nuclear force.

What Is An Atom And How Do We Know?

Basic Atomic Structure: A Look Inside the Atom

What affects the magnitude of the deflection of the cathode ray in Thomson’s experiment?

Label the following statements about J. J. Thomson’s cathode-ray tube experiments shown in Figure 2.6 as true or false. 
(b) A cathode ray is a stream of charged particles.

How Small Is An Atom? Spoiler: Very Small.

The Atom Example 2

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9. Quantum Mechanics

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11. Bonding & Molecular Structure

12. Molecular Shapes & Valence Bond Theory

13. Liquids, Solids & Intermolecular Forces

14. Solutions

15. Chemical Kinetics

16. Chemical Equilibrium

17. Acid and Base Equilibrium

18. Aqueous Equilibrium

19. Chemical Thermodynamics

20. Electrochemistry

21. Nuclear Chemistry

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23. Chemistry of the Nonmetals

24. Transition Metals and Coordination Compounds

[BOOK CHEM] Clutch Version

Millikan Oil Drop Experiment

The Oil Drop Experiment helped with determining the fundamental charge of the electron.&nbsp;

Ions

Ions represent elements that possess either a positive charge or a negative charge.&nbsp;

Periodic Table: Charges

Elements lose or gain electrons to have the ideal number of outer shell electrons like the noble gases.&nbsp;

Law of Definite Proportions

"Different samples of a pure chemical compound always contain the same proportions of elements by mass."

Periodic Table: Classifications

The Periodic Table contains 3 Major Classifications when describing its elements

Isotopes

Isotopes are atoms of an element that have the same atomic number, but different mass number.&nbsp;

The atom represents the basic functional unit in chemistry

Mole Concept

The Mole Concept involves the interconversions between different unit amounts of a substance.

Periodic Table: Representative Elements & Transition Metals

The Groups of the Periodic Table can be broken down into the Representative Elements and Transition Metals

Atomic Theory

John Dalton, one of the "Fathers of Chemistry"is credited with modernizing the Atomic Theory.

Subatomic Particles

The atom is composed of 3 subatomic particles:neutrons, protons, and electrons.

Periodic Table: Elemental Forms

The elements of the Periodic Table exist in different elemental forms in the natural world

Periodic Table: Phases

Under standard conditions of temperature and pressure, the elements can exist as solids, liquids or gases

Atomic Mass

The atomic mass of an element includes the masses of all 3 subatomic particles of neutrons, protons and electrons.&nbsp;

Periodic Table: Group Names

The Periodic Table can be further classified into Periods and Groups.&nbsp;

Law of Conservation of Mass

"In a chemical reaction, no matter is created or destroyed, but instead changes form."

Calculating Molar Mass

Molar Mass is a physical property that represents the mass of a substance divided by the amount of that substance.

Rutherford Gold Foil Experiment

The Gold Foil Experiment helped with the discovery of the positively charged nucleus.

Law of Multiple Proportions

“When 2 elements (A &amp; B) form different compounds, the mass of Element B that combine with 1 g of A are a ratio of whole numbers."

Periodic Table: Element Symbols

The Element Symbols of the Periodic Table represent the abbreviated form of an element

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