Unit 2: Chemistry Flashcards by Al Sun

What is a pure substance? Give an example.

Consists of only one type of particle, all of them will have same physical properties, e.g. sugar, water, anything on periodic table

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What is an element?

Particle with one type of atom

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What is a compound?

Molecule with more than one type of atom

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Can a pure substance only be an element or compound, or both?

Both an element or a compound.

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What is a mixture, in general? What are the three types of mixtures?

More than one type of particle (element/compound). Three types: mechanical, solution, and alloy

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What is a mechanical mixture? Give an example.

Mixture that has two or more visible phases (easily seen w/ naked eye, microscope), e.g. pizza, trail mix

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What is a solution? Give an example.

Mixture that has just one visible phase, e.g. apple juice, bleach

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What is an alloy? Give an example.

A solution of metals, e.g. brass, bronze

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Are mechanical mixtures homogeneous or heterogeneous?

Heterogeneous.

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Are solutions and pure substances homogeneous or heterogeneous?

Homogeneous.

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Define ‘chemical property’.

the potential for a substance to undergo chemical change

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Give at least six examples of chemical properties.

reacts with water, air, oxygen, acids, other pure substances

toxicity, stability, combustibility

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Define ‘physical property’.

A property that does not change the chemical nature of the substance

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Give at least five examples of qualitative physical properties.

colour, taste, smell, texture, state, crystal shape, brittleness, malleability

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Give at least five examples of quantitative physical properties.

lustre, hardness, viscosity, solubility, melting and boiling temperatures, density, electrical and heat conductivity

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What is malleability?

ability to be hammered into a sheet

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What is ductility?

ability to be stretched into a wire shape without breaking

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If a substance is the opposite of brittle, what is it?

flexible

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What is lustre?

Ability to reflect light

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What is hardness?

Resistance to being scratched

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What is viscosity? If a substance has high viscosity, what does that mean?

Resistance to flow, high viscosity means it flows slowly

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What is solubility?

How well a substance dissolves into another substance

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What is density (describe)?

Amount of matter in a certain volume

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What is the equation for density?

D=m/v

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What is the equation for mass in terms of density and volume?

m=DV

What is the equation for volume in terms of density and mass?

V=m/D

What are the physical characteristics of metals? (4)

lustrous, good heat and electricity conductors, malleable and ductile, usually solid at room temperatures

What are the physical characteristics of nonmetals? (5)

not lustrous, poor heat and electricity conductors, brittle, not malleable/ductile, vary from solid to gas

What are the chemical characteristics of metals? (2)

tend to lose electrons (become pos. charged ions), corrode easily (e.g. oxidize)

What are the chemical characteristics of nonmetals? (1)

tend to gain electrons (become neg. charged ions)

What is the periodic table trend for atomic number and atomic mass?

increases down and right

What is the periodic table trend for atomic size?

increases down and left

What is the periodic table trend for hardness?

metals softer down and left, nonmetals softer up and right

What is the periodic table trend for reactivity?

metals more reactive down and left, nonmetals more reactive up and right

What is the ratio of compounds in a water molecule?

Ratio of 2 hydrogen atoms to 1 oxygen

Where on the periodic table are alkaline metals? Where are alkaline earth metals? (List the family #)

Alkaline metals: Family 1, alkaline earth: Family 2

What is the ionic charge of alkaline metals?

What is the ionic charge of alkaline earth metals?

What is the ionic charge of halogens?

-1

What is the ionic charge of noble gases?

What are the characteristics of alkaline metals? (2)

react with water to make an alkaline solution, very reactive

What are the characteristics of alkaline earth metals? (2)

easily found in ground, form alkaline solutions when placed in water

What are the characteristics of halogens? (1)

readily form gases

What are the characteristics of noble gases? (1)

largely unreactive

How are ionic charges formed?

Atoms losing or gaining electrons, resulting in an overall positive or negative charge

What is the history of the atomic model?

Democritus discovered that all matter can be divided into smaller pieces until a single indivisible particle is reached, named it the ‘atom’ Aristotle rejected Democritus’ idea, had water/earth element theory, different elements have UNIQUE PROPERTIES Dalton discovered that all atoms of an element are identical, atoms are rearranged to form new substances in chemical reactions - billiard ball model Thomson discovered extremely small negatively charged particles emitted by hot materials, called them electrons - plum pudding model because he thought that electrons were evenly distributed throughout atom Rutherford discovered that the centre of that has positive charge (nucleus, contains most of atom’s mass), surrounded by electron cloud, most of atom is empty space, discovered proton in nucleus Chadwick discovered a particle that could penetrate and disintegrate atoms - 0 charge (neutrons), neutrons add mass to atom - created planetary model of the atom Bohr discovered that atoms have different orbits, electrons can jump between them and release energy & light when they go from higher to lower orbits - Bohr-Rutherford diagrams

What are the postulates of Dalton's atomic theory?

- All matter is made of tiny atoms, that are indivisible - All atoms of an element are identical, atoms of different elements are different - Atoms are rearranged to form new substances in chemical reactions - Compounds are formed by a combination of two or more different atoms

What is an ionic bond between? What are their charges after the bond?

Metal and nonmetal, positive and negative

In an ionic bond, are electrons shared or transferred?

Transferred

What is a covalent bond between?

Nonmetal and nonmetal

In a covalent bond, are electrons shared or transferred?

Shared

Define 'molecular compound'.

Covalently bonded elements that are different (nonmetals bonded with nonmetals)

Define 'ionic'.

With charge

What is a cation?

positively charged ion

What is an anion?

negatively charged ion

Define 'ionic compound'.

Nonmetal and metal ionically bonded

What is a molecular element? Give two examples.

Same elements bonded together, e.g. O2, H2

What gas is present when a burning splint makes a 'pop!'

hydrogen

What gas is present when lime water bubbles and becomes cloudy?

carbon dioxide

What gas is present when a glowing splint bursts into flame?

Oxygen

What gas is present when cobalt chloride paper changes colour?

Water vapour