Chapter 4 - Chemical Foundations: Elements, Atoms, and Ions Flashcards
(42 cards)
What are the 2 applications of chemistry that were used before 1000 BC?
the processing of ores to produce metals for ornaments and tools and the use of embalming fluids
What were the four fundamental substances that the Greeks had proposed matter to have composed of in 400 BC?
fire, earth, water, and air
Some alchemists were what?
mystics and fakes who were obsessed with the idea of turning cheap metals into gold
Which elements were found by alchemists?
mercury, sulfur, and antimony
What did alchemists learn how to do?
to prepare acids
Who was the first scientist to recognize the importance of careful measurements?
Robert Boyle (1627-1691)
What was Boyle’s most important contribution to science?
his insistence that science should be firmly grounded in experiments (his definition of element was based on experiments)
Why couldn’t air be considered an element?
because it could be broken down into many pure substances
All matter can be broken down chemically into about how many different elements?
100
How many different elements are known? And how many of those occur naturally?
115; 88
What are the 5 most abundant elements in the Earth’s crust, oceans and atmosphere? (List in order of abundance)
Oxygen (49.2%), silicon (25.7%), aluminum (7.50%), iron (4.71%), calcium (3.39%)
What are the elements that are the basis for all biologically important molecules?
Oxygen, carbon, hydrogen, and nitrogen
What are trace elements?
elements found in the body that are crucial despite their small amounts
how many known substances are composed of elements?
millions
What is the microscopic form of an element?
the single atom of the element
What is the macroscopic form of an element?
a sample of the element large enough to weigh on a balance
What does the law of constant composition state?
a given compound always has the same composition regardless of where it comes from
State Dalton’s atomic theory (1808)
1) elements are made of tiny particles called atoms
2) all atoms of a given element are identical
3) the atoms of a given element are different from those of any other element
4) atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative numbers and types of atoms
5) atoms are indivisible in chemical processes. Atoms are not created or destroyed in chemical reactions. A chemical reaction simply changes the way the atoms are grouped together
Who was J.J. Thomson?
showed that all types of atoms must contain negative particles or electrons; he also concluded that atoms contained positively charged particles to balance the electrons
Who was William Thomson or Lord Kelvin?
introduced the plum-pudding model of an atom
Who was Ernest Rutherford?
introduced the idea of a nuclear atom, contrary to the plum pudding model
What is a nuclear atom?
atom with a dense center of positive charge (nucleus) surrounded by tiny electrons moving in empty space
When did Rutherford conclude that the nucleus of the atom contained protons?
1919
Who showed that nuclei contained neutrons?
Rutherford and James Chadwick (1932)
