Elements and compounds Flashcards

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1
Q

Element

A

a pure substance made up of only one type of atom

(eg. gold atoms make up the element of gold or AU)

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2
Q

A chemist heats up some pure ammonia to very high temperature and finds that it breaks down into two other gases.

Explain whether ammonia is an element or not.

A

Ammonia is not an element as it is made up of two different atom types which separated in the form of gases.

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3
Q

Noble gases

A

elements that are found in singular atomic form

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4
Q

molecules

A

single atoms bonded together chemically

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5
Q

Most elements have a structure of

A

lattices

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6
Q

Lattices

A

Multiple atoms that are chemically bonded together in continuous framework

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7
Q

Which state of matter do lattices form?

A

Solids due to the crystal structure

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8
Q

Which state of matter do molecules form

A

liquid and gases and solids

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9
Q

which state of matter do single atoms form?

A

gases

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10
Q

properties

A

a determination of how an element reacts or behaves

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11
Q

properties of metal

A
  • conducts heat
  • conducts electricity
  • ## shiny appearance
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12
Q

When writing a chemical formula, what are the rules for the order of the elements?

A

If the elements are in the same column, the element on the bottom goes first.

The element on the left of the periodic table row is written first.

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13
Q

Where are most of the non-metal elements held in the periodic table?

A

In the upper right corner

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14
Q

In the periodic table, barium sits directly underneath strontium. Propose two things that you can say about barium and strontium with just this information.

A

Barium has similar properties to Strontium and Strontium has less atomic weight than Barium.

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15
Q

Compounds

A

substance that has atoms of two or more elements (atom types) joined together through chemical bonds

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16
Q

mixture

A

combination of substances that are not chemically bonded so they can actually be separated physically.

17
Q

Water is a compound of Hydrogen (H) and Oxygen (O). Its chemical formula is H2O.

Determine the number and type of atoms in each molecule of WATER.

A

Water has two hydrogen atoms and one oxygen atom.

18
Q

Sulfur dioxide is a gas released by volcanoes. Each molecule contains one sulfur (S) atom and two oxygen (O) atoms.

Identify its chemical formula.

A

SO2

19
Q

Determine the general structure of a word equation.

A

Reactants -> Products

20
Q

Periodic

A

Occurring at intervals/ recurring

21
Q

Summarise the difference between exothermic and endothermic reactions.

A

Exothermic reactions overall release energy (heat) so the temperature of the surroundings increases.

Endothermic reactions overall absorb energy (heat) so the temperature of the surroundings decreases.

22
Q

Breaking bonds

A

A process that requires energy from surroundings

23
Q

Making bonds

A

A process that releases energy back into the surroundings

24
Q

Do both endo- and exothermic reactions require energy and release energy?

A

YES

The two steps – the first requiring energy and the second releasing it – take place in all reactions, exothermic and endothermic. The difference is whether the amount of energy released when the new bonds form is greater or less than the energy required to break the old bonds.

25
Q

Activation energy is:

A

needed to break the bonds in the reactant molecules

26
Q

If the amount of energy released by a reaction is greater than the activation energy needed to start it then, then we can infer that the reaction must be:

A

exothermic, because overall energy is released

27
Q

Chemical energy

A

Chemical energy is the energy that is stored in a compound’s chemical bonds

28
Q

Do products have more or less energy than the reactants in an endothermic reaction?

A

MORE

In endothermic reactions, the products have more chemical energy than the reactants. So the extra energy is absorbed from the surroundings.

29
Q

Do products have more or less energy than its reactants in exothermic reactions?

A

LESS

In exothermic reactions, the products have less chemical energy than the reactants. So the extra energy is released to the surroundings.

30
Q

Monatomic substances

A

Elements found in single atoms

31
Q

What are the three different arrangements elements can be found in?

A

Single atoms, molecules, lattices

32
Q

The arrangement of the element decides the physical properties.

TRUE or FALSE

A

True

The arrangement of the element decides the physical properties.

33
Q

How many known elements are there currently?

A

118!

34
Q

Atomic number

A

The number of protons in the nucleus of an atom.

35
Q

Do metals have high melting and boiling temperatures

A

yes!

36
Q

Are metals malleable?

A

YUP!!!!!!!!