science section I

Prior to the 17th century, what field that involved mystical or supernatural explanations for natural phenomena often overlapped with Chemistry?

Alchemy

During the 17th century and beyond, there was a transition from Mysticism to what belief?

Empiricism, which is the development of scientific conclusions based on evidence gleaned from scientific experiments

Atoms are what?

The smallest distinct particles that make up matter.

Atoms that gain or lose electrons are called what?

Ions

What is one way to measure Atomic Mass?

A way to do so is by measuring the relative masses of said atoms that combine to form compounds

In Modern laboratories, what is a tool that can be used to accurately measure the mass of a single atom?

Mass Spectrometers

What is one of the uses of Mass Spectrometers outside of a lab setting?

Mass Spectrometers can be used at airports to check that passengers are not carrying compounds that are typical explosives.

What are the 3 parts of a Mass Spectrometer?

1. An ion source where compounds or atoms are converted into (usually positive) ions.

2. A mass analyzer where the ions are accelerated in magnetic fields and take different pathways.

3. A detector that measures the number of ions of each mass that are present.

What fields did John Dalton (1766-1844) contribute to the most?

Chemistry, Meteorology, and Physics

What Greek philosophers held beliefs that were the predecessors to John Dalton's idea of Atomicism?

Leucippus and his student Democritus.

What were some of John Dalton's conclusions that were presented to the Manchester Literary and Philosophical Society (1800-1844)?

Dalton found that the variation of vapor pressure for all liquids was the same, if given the same variation in temperature and constant pressure. Dalton also observed that at constant pressure, different liquids expanded the same amount if they were subjected to the same increase in temperature. These observations led Dalton to formulate what eventually became known as Dalton's Law of Partial Pressures, which stated that the total pressure of a mixture of gases is equal to the sum of the pressures of each individual gas.

What is the formula to Dalton's Law of Partial Pressures?

P(Total) \= P(A) + P(B).

A and B are gases that compose the Total.

Which two French Scientists did Dalton drew much of his research from?

Antoine Lavoisier and Joseph Louis Proust.

What scientific law did Lavoisier propose in 1789?

The law of conservation of mass, which stated that during a chemical reaction, matter is neither created nor destroyed, and thus the mass of the reactants is equal to the mass of the products.

What scientific law did Proust put forth in 1799?

Proust's law of definite proportions, which stated that a substance is always composed of the same proportion of each element.

Building upon Proust's and Lavoisier's concepts, Dalton came up with what?

The Law of Multiple Proportions, postulating that if two elements combine to form more than one compound, the ratios of their masses are whole numbers that are determined by the atomic weights of the elements involved

What did Dalton publish in 1808?

A New System of Chemical Philosophy.

What are some of Dalton's major conclusions, concerning Atomic behaviour?

All matter is composed of very small, indivisible particles called atoms.

Atoms of the same element have the same properties (size, mass, etc.) while atoms of different elements will have different properties (e.g., hydrogen has different properties than lead).

Atoms cannot be divided any further and cannot be created or destroyed.

Atoms of different elements can combine in whole-number ratios to form compounds.

Chemical reactions can cause atoms to combine, separate, and rearrange.

What is the symbol for electrons?

e-

What is the symbol for protons?

p+

What is the symbol for neutrons?

n^0

What element does not have neutrons?

Hydrogen

What is an Isotope?

Atoms with the same number of protons but different number of neutrons

What is the symbol format for Isotopes?

ᴬₑ(x)

X is the element symbol, e is the atomic number or number of protons in the nucleus of the atom, and A is the mass number, which is equal to the number of neutrons plus the number of protons.

What is a nuclide?

A distinct kind of nucleus characterized by a specific number of protons and neutrons.

How do you calculate the amount of neutrons?

Neutrons \= Mass Number - Protons

What is an Atomic Mass Unit?

Also known as a Dalton, the Atomic Mass Unit is 1/12 the mass of a C-12 atom

Do isotopes have the same chemical properties?

Yes, because they have the same number of protons and electrons

What is Deuterium?

An isotope of Hydrogen that has 1 Neutron

How can Deuterium be used?

Deuterium can be used as a "tracer" to find out how chemical reactions of Hydrogen occur. It is also widely used in fusion reactors as it combines in a fusion reaction with another isotope of hydrogen, tritium, to release large amounts of energy.

How is 14 6 Carbon formed?

It is formed in the upper atmosphere as a result of cosmic rays hitting nitrogen atoms. It mixes with atmospheric carbon dioxide and then becomes part of the biosphere, entering the bodies of all living systems.

What are some of the uses of 14 6 Carbon?

Carbon dating; tracer to observe what happens to carbon atoms in chemical and biochemical reactions; work out the detailed chemistry of photosynthesis and respiration reactions in plants and animals; climate change.

What has 60 27 Co been used to treat? What are some of its other applicability?

Cancerous Tumors. It may also be used to kill harmful Bacteria to sterilise food in order that it may be stored longer and it can also be used to examine steel components and welds for possible flaws.

How do you calculate Weighted Averages of Isotopes?

Change each percent abundance into decimal form by dividing by 100. Multiply this value by the atomic mass of that isotope. Add together for each isotope to get the average atomic mass.

Electrons must occupy a certain what in an atom?

Energy Level

The absorption of what substance is needed to excite electrons to a higher energy level?

A Quantum of Light Energy, also known as the Photon.

When the atom returns to a lower energy state, what can be emitted?

A Photon.

The process of examining absorbed and emitted photons for their energy is called what?

Absorption Spectrum or Emission Spectrum.

What is the Bohr model?

A diagram showing all electrons in an atoms within their appropriate energy levels (looks like a solar system)

How many electrons can each orbital hold?

2 electrons

What is the Quantum Mechanical Model?

This atom model displays the electrons to be not at exact distances or fixed locations and do not rotate in orbits since electrons are shown to have wave like properties.

All matter is known to exhibit properties of what?

Particles and Wave

What is the Photoelectric effect? And what does this have to show about Light?

The Photoelectric Effect is where a light (Photon) transfers its energy to an electron, which then is emitted from a metal surface. This effect clearly shows Light as behaving like a particle.

Where is the Photoelectric effect used?

Digital Cameras

What is an Electron "Cloud"?

A region around the nucleus of an atom where electrons are likely to be found

In the Modern Periodic Table, elements are arranged in what order?

The increasing atomic number.

What are the horizontal rows on the periodic table called?

Periods

What are the vertical columns on the periodic table called?

Groups

What is Atomic Radius?

Size of an atom. As one proton and one electron are added to an atom, there is one more proton to attract the electrons. If the added electrons are approximately the same distance away from the nucleus, then the increased attraction will shrink the radius or size of the atom.

How is the Atomic Radius represented on the Periodic Table?

From left to right of the Table, the Atomic Radius decreases.

What is the Ionisation energy of an atom? And what does it measure about the atom?

The energy needed to remove an electron from the ground state of an atom. The Isonisation energy measures the force of attraction holding the electron to the nucleus.

As the number of protons increases, what?

The force of attraction increases

What is Electron Affinity?

A term applied to an atom as a measure of the fact that most neutral atoms still exhibit a small attraction for an electron.

What is increased down the Periodic Table?

The Atomic Radius, which is due to the increase in the distance of the outer electrons from the nucleus due to the added electron shell.

What happens to the Ionisation Energy down the Periodic Table?

It decreases because of the extra distance from the outer electrons to the nucleus, and thus there is a reduced attractive force.

What happens to Electron Affinity down the Periodic Table?

It decreases as a result of the extra distance from the electrons to the nucleus, thus there is a reduced residual attractive force.

What is Electronegativity?

A measure of the tendency of an atom to attract a bonding pair of electrons

The higher value of Electronegativity (EN) results in what?

The greater the attraction for neighboring Electrons.

If EN values are greater than 1.8, what sort of bond is present?

Ionic Bonds

Atoms with an EN value between 0.5 and 1.8 have what sort of bond?

Covalent Bonds

What is a Dipole moment?

A dipole moment is a measurement of the separation of two opposite electrical charges.

What is a Chemical Compound?

A substance that composes of atoms of elements that cluster together in arrangements that only break apart if energy is applied.

What is the specific arrangement of the forces between two atoms called?

A Chemical Bond.

What is a Molecule?

A group of atoms held together in a constant ratio by strong covalent bonds is often called a molecule

What is a Chemical Formula?

A combination of symbols that shows the ratio of elements in a compound

What are the forces between Molecules that determine the physical properties of a substance called?

Intermolecular forces

What are Electrostatic forces?

Forces of attraction between positive and negative charges.

What is an Ionic Bond?

A chemical bond that's formed when an Atom transfers and electron to another Atom. Thus, resulting in a positive and negative Ion that are strongly attracted to each other.

What is a Cation? Anion?

Cation: positive ion

Anion: negative ion

What is a Covalent Bond?

A chemical bond formed when two or atoms share electrons.

What is a Metallic Bond?

Metallic bonds is a Chemical Bond, generally of the same element, in which electrons are bounded in such a way as to allow many electrons to move more freely among the atoms.

What is an alloy? What is an example of an alloy?

A solid or liquid mixture of two or more metals. Brass is an example of an alloy.

If the Covalent Bond is between two identical atoms, then it is said to be what?

Non-Polar

What is a Polar Covalent Bond?

A covalent bond in which electrons are not shared equally between Atoms.

What are Van der Waals forces?

A slight attraction that develops between the oppositely charged regions of nearby molecules

True or False: Intermolecular forces are weaker forces of attraction than intramolecular forces

True

Molecules are said to be Polar if what?

If the distance between the centre of the Positive Charge and the centre of the Negative Charge can be measured. Also, Polar Molecules are also said to have a dipole moment, meaning that a rotational force will exist if the molecule is placed in an electric field.

What is the difference between Polar and Non-Polar Molecules?

Polar molecules occur when there is an electronegativity difference between the bonded atoms. Nonpolar molecules occur when electrons are shared equal between atoms of a diatomic molecule or when polar bonds in a larger molecule cancel each other out.

What is an Induced Dipole?

A weak attraction that results from a polar molecule inducing a dipole in an atom or in a nonpolar molecule by disturbing electron arrangement of the nonpolar species

What is a Temporary Dipole?

A momentary induced dipole created when a polar molecule distorts the electron cloud of a nonpolar molecule

What are London Dispersion Forces?

First delineated by German Physicist Fritz London (1900 - 54), London Dispersion Forces is the intermolecular attraction between any two particles resulting from the polarization of the electrons in the electron clouds. The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles.

What is a Hydrogen bond?

The attraction between a hydrogen atom with a partial positive charge and another atom with a partial negative charge

What elements are strongly electronegative?

Oxygen (O), Nitrogen (N), and Fluorine (F)

What do hydrogen bonds do?

Hydrogen bonds play important roles in the structure and function of many biological molecules like proteins and deoxyribonucleic acid (DNA).

What two scientists in 1950 developed a model of DNA that portrayed it as a Double-Helix as a result of Hydrogen Bonds?

James Watson and Francis Crick

Whose X-ray studies did James Watson and Francis Crick base their work on?

Rosalind Franklin and Maurice Wilkins

By dissolving metals in acids, which resulted in Hydrogen, what Alchemist unknowingly produced Hydrogen in the early 16th century?

Paracelsus (1453-1541)

Which Anglo-Irish Chemist in 1671 noted that a flammable gas (Hydrogen) was produced when iron was dissolved in acid?

Robert Boyle

What did Robert Boyle note about Hydrogen?

That Hydrogen was less than air.

Which British chemist identified Hydrogen as an element distinct from other gases and described its properties in great detail in 1766?

Henry Cavendish (1731-1810)

What were previously thought as the only basic elements?

Water and Oxygen.