Chapter 8 Review!!! Guided Notes type

By ​ (a)   , a total of 63 elements had been discovered. A few were gases. Two were ​ (b)   . Most were solid metals. Some reacted explosively as they formed compounds. Others reacted slowly. Scientists wondered if the properties of elements followed a pattern. Dmitri ​ (c)   discovered a ​ (d)   that applied to all the elements.

• 1869
• liquids
• Mendeleev
• set of patterns

Mendeleev noticed that a ​ (a)   of ​ (b)   appeared when he arranged the elements in order of increasing ​ (c)   He found that the properties ​ (d)   regularly.

• pattern
• properties
• atomic mass.
• repeated
• atomic number

Mendeleev created the first periodic table in ​ (a)   . A ​ (b)   is an arrangement of elements showing the ​ (c)   pattern of their ​ (d)   .​ (e)   means "in a regular, repeated pattern."

• 1869
• periodic table
• repeated
• properties
• Periodic

Mendeleev left ​ (a)   . He ​ (b)   the spaces would be filled by the ​ (c)   that had not been discovered yet.

• blank spaces
• predicted
• elements

As scientists discovered new elements, the periodic table changed. The ​ (a)   of the table also changed when people learned more about ​ (b)   . To understand the periodic table you need to know something about atoms too.

• organization
• atoms

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NGSS.MS-PS1-1

Atoms were once thought of as the ​ (a)   particles of matter. But starting in the late 1800s, scientists found that ​ (b)   are made of even smaller parts. Look at the simple model of an atom shown here.

• atoms
• smallest

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NGSS.MS-PS1-1

At the very center of an atom, is the ​ (a)   (noo klee us; plural, nuclei). It contains positively charged particles called ​ (b)   . Every atom of the same element has the same ​ (c)   , called the ​ (d)   . Elements can be identified by their atomic number. 

• nucleus
• protons
• number of protons
• atomic number

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NGSS.MS-PS1-1

Moving around the space outside the nucleus are ​ (a)   charged particles called ​ (b)   . A neutral atom has the ​ (c)   of electrons as it has protons

• negatively
• electrons
• same number

Atomic number - The first piece of information is the number 19, the atomic number of potassium. Every potassium atom has 19 protons.

How many protons does Potassium have?

• 45

• 58

• 87

• 19

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NGSS.MS-PS1-1

Chemical symbol - Just below the atomic number is the letter K- the chemical symbol for potassium. Chemical symbols contain either one or two letters. Often, an element's symbol is an abbreviation of the element’s name in English. Other elements have symbols that are abbreviations of their Latin names.

What is the symbol for potassium?

• K

• Br

• Hg

• P