Unfortunately, the patterns to English pronunciation are very complicated. There is no single pattern. And many of the patterns that do exist have some exceptions.
If you're not already familiar with the concept of how English vowel letters correspond to "long" and "short" pronunciations, please read the section below titled "Phonics: basic overview".
Adjectives ending in "-al" are usually stressed on the third-to-last or second-to-last syllable. There are certain conditions that make one stress pattern more likely than the other, but they're somewhat difficult to explain, and there are exceptions to them. I tried to give an overview in my answer to the following question: “Substantival” - doesn't fit the normal stress paradigm
Abstract nouns ending in the suffix "-ity" are stressed on the third-to-last syllable, and a single vowel letter in this syllable generally receives its "short" pronunciation, unless it's a "u" followed by only a single consonant and then another vowel letter. Examples: serene /səˈriːn/, serenity /səˈrɛnɪti/; diverse /dɪˈvɜrs/, diversity /dɪˈvɜrsɪti/; divine /dɪˈvaɪn/, divinity /dɪˈvɪnɪti/. As the answer to the linked question explains, there are basically no exceptions to the stress rule for nouns ending in the suffix -ity. There are at least a few words that violate the short-vowel rule, such as obesity /oʊˈbiːsɪti/ (pronounced with a "long e" nowadays).
Disyllabic verbs such as deprive are often stressed on the last syllable.
Abstract nouns ending in "-ation" are generally stressed on the second-to-last syllable. I don't know if there are any exceptions.
As far as I know, it's not a rule, but there are a fairly large number of nouns ending in -y that have stress on the third-to-last syllable, such as prophecy, hypocrisy, and all words ending in -ology or -onomy.
Adjectives ending in "-ic" are generally stressed on the second-to-last syllable, and a single vowel letter in this syllable receives its "short" pronunciation if it comes before a consonant. Examples: crisis /ˈkraɪsɪs/, critic /ˈkrɪtɪk/; emphasis /ˈɛmfəsɪs/, emphatic /ɛmˈfætɪk/; tone /toʊn/, tonic /ˈtɒnɪk/. There are a small number of words that violate the stress rule, such as lunatic, and a greater number of exceptions to the short-vowel rule such as basic (pronounced with a "long a").
Phonics: basic overview
There isn't enough space here to give a full description of English “phonics” here (heuristics for figuring out the pronunciation of a word from its spelling) so my original answer assumed that you already know some of this, as you seem to be an intermediate-level learner.
In general, in stressed syllables, the single English vowel letters "a", "e", "i", "o", "u" can correspond in pronunciation to either of two different vowel sounds (phonemes). One of these pronunciations is often designated “long”, and the other “short”. Please don’t interpret these names as phonetic descriptions of the vowels in these classes. They aren’t, although there are some historical and theoretical reasons for these names. You can just think of them as arbitrary labels for two sets of vowels. A somewhat common terminological alternative in linguistics is to speak of "tense" (= "long") and "lax" (="short") vowels, but sometimes this refers to a slightly different concept.
In British English, the “long” pronunciations are transcibed as follows in IPA using the “Gimson quantitative-qualitative scheme”: a /eɪ/ as in "date", e /iː/ as in "feed", i /aɪ/ as in "life", o /əʊ/ as in "note", u /juː/ as in "cute". The “short” pronunciations are a /æ/ as in "cat", e /ɛ/ as in "bet", i /ɪ/ as in "bit", o /ɒ/ as in "hot", u /ʌ/ as in "bud".
In unstressed syllables, any vowel letter may correspond to yet another vowel sound: the schwa /ə/. In the terminology I'm using, schwa doesn't belong to either the class of "long" or "short" vowels: it's in a class of its own. Due to a process called "vowel reduction", a schwa in one word may correspond to pretty much any other vowel in another related word with a different stress pattern.